GTA
Airguns by Make and Model => Diana Airguns => Topic started by: HectorMedina on January 13, 2020, 01:35:23 PM
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https://www.ctcustomairguns.com/hectors-airgun-blog/the-saga-of-a-56-th (https://www.ctcustomairguns.com/hectors-airgun-blog/the-saga-of-a-56-th)
A four part, in-depth, study of the two current "philosophies" in powerplant design.
Guest blog by our own Steve Herr.
Hope you enjoy!
HM
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Yup ... factory Crowning is seldom ideal and attention to such details can make or break an otherwise excellent tuning effort.
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Hector how much does something like that cost to do?
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Hector how much does something like that cost to do?
Jay;
If you mean the re-crowning, it usually is part of all the "barrel work" in a tune and costs about $75
Most of the times we are not faced with the need to remove almost 1/8" off the muzzle
This was a very particular case that needed a LOT of work.
IF you have such a lop-sided crown you may need to pay up to $150, it's simply the time it takes to get everything setup and squared properly.
Hope this answers your question.
Keep well and shoot straight!
HM
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Mine in .22 shoots pretty darn good but still going to inspect that crown. Where are my glasses?
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Hector how much does something like that cost to do?
Jay;
If you mean the re-crowning, it usually is part of all the "barrel work" in a tune and costs about $75
Most of the times we are not faced with the need to remove almost 1/8" off the muzzle
This was a very particular case that needed a LOT of work.
IF you have such a lop-sided crown you may need to pay up to $150, it's simply the time it takes to get everything setup and squared properly.
Hope this answers your question.
Keep well and shoot straight!
HM
That's still a good price Hector. I never seen a price list nor what is all involved in it.
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Mine in .22 shoots pretty darn good but still going to inspect that crown. Where are my glasses?
Or if you’re like me.....glasses AND magnifying glass😁
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I had been visiting Fowler's Gun Room in Orange, CA where I started my parish ministry back then. I saw an High Standard .22 Match pistol brand new for sale and examined the muzzle which clearly showed more barrel on the right than the left like an extension problem there. To me I had thought the handgun wouldn't shoot inaccurately since the same exit (damaged crown or misdrilled crown) touched the bullet the same way out the barrel. I didn't get that Match gun because something in my head was telling me an imperfect crown is NOT a good thing even though I didn't know why technically.
So now I see this detailed example on a crown needing repair and thank Hector for showing it. ::)
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Wonderful! I've been waiting for this update. I'm eager to learn what y'all learned and did. Although no one seemed interested in responding to my post about removing the cocking bracket from my D56, doing so really helped tighten up the groups on my rifle. However, I haven't given the crown much attention. Removing the cocking bracket smoothed out the recoil so much that now, through the scope, I can watch the pellet fly all the way to impact. Really cool! I really wish there was something that can be done about the lateral rocking from the slide rails but I don't think those brackets that hold the rails are removable from the rifle's action. On the rear rail bracket, one of the holes for the rail is too big. The holes in the slides are fine. I've rotated the rails around to be sure that the rails themselves aren't different sizes. Its the bracket, not the slide or the rail.
Could a regular PB gunsmith recrown an airgun? I'd rather bring my rifle to a local gunsmith than to mail it off but what ever is best. I can lap a crown but I can't cut one square if needed.
Can't wait to read about the rest of the story!
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Wonderful! I've been waiting for this update. I'm eager to learn what y'all learned and did. Although no one seemed interested in responding to my post about removing the cocking bracket from my D56, doing so really helped tighten up the groups on my rifle. However, I haven't given the crown much attention. Removing the cocking bracket smoothed out the recoil so much that now, through the scope, I can watch the pellet fly all the way to impact. Really cool! I really wish there was something that can be done about the lateral rocking from the slide rails but I don't think those brackets that hold the rails are removable from the rifle's action. On the rear rail bracket, one of the holes for the rail is too big. The holes in the slides are fine. I've rotated the rails around to be sure that the rails themselves aren't different sizes. Its the bracket, not the slide or the rail.
Could a regular PB gunsmith recrown an airgun? I'd rather bring my rifle to a local gunsmith than to mail it off but what ever is best. I can lap a crown but I can't cut one square if needed.
Can't wait to read about the rest of the story!
It's quite normal to be able to see the pellet fly to the target in a 54 or a 56 as long as the lighting conditions are good. It would seem to me that your "fin" was creating some problem with the action as it slid.
You CAN ream and replace the pins/rails by the next following size, you just need to be extra careful not to disalign anything.
I've also seen guns where the proper metric size pins were substituted and the SAE "equivalents" proved to be similar, but not the same. The bronze sleds are fairly easy to ream out to the next size.
It is important to note that there is NO CONTACT between the slides and the bracket's bottoms, except for the balls that the slides have. So, while polishing these surfaces can look good, the balls themselves will polish with use the channels that need polishing. Just a question of shooting enough your gun.
Firearms gunsmiths CAN recrown airgun barrels if they are extra careful and follow your instructions. Make sure you find out how they re-crown barrels because you cannot take the barrel out of the action, as in a lot of PB's. So they will need a lathe with at least 1.5 " hole through spindle, or they will need to build a special jig. If lathe turned, ask for a dished Match Crown, look carefully at this crown:
(https://imagizer.imageshack.com/img651/4828/d34kp20matchcrown.jpg)
If they use handtools, then make sure they will turn a brass (not bronze and not steel) pilot to the specific internal diameter of your lands at the choke, and that they will cut an 11 degree crown with a flat dish at least 1/3 of the surface to protect it.
Airguns need special crowns because of the shape of the most common projectile and the slow velocity of the pellet in relation to the propelling pressure wave.
HTH
HM
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I'm curious the thinking that the muzzle weight is too heavy. It is substantial, no doubt about that, but seems to add to the balance of what is a heavy gun.
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I'm curious the thinking that the muzzle weight is too heavy. It is substantial, no doubt about that, but seems to add to the balance of what is a heavy gun.
You are right in the sense that the T/H stock has more wood at the rear. So, yes, in a way, it "balances".
BUT it is a bit too heavy for the attachment system chosen, AND it is not adjustable.
Unless you are like Steve, that tunes the MV to the pellet without any power constraints, you really need something else.
BUT, that is another chapter ;-)
HM
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[
Airguns need special crowns because of the shape of the most common projectile and the slow velocity of the pellet in relation to the propelling pressure wave.
HTH
HM
Hector,
If the pellet leaves the barrel at 800 fps, what is the approximate speed of the "propelling pressure wave"?
Thanks,
Yogi
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awaiting the rest of the installments.......
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awaiting the rest of the installments.......
Patience, my young grasshopper.
Allow Steve some time for fun!
;-)
HM
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awaiting the rest of the installments.......
I’ll try to finish the write-ups this weekend ;)
Steve
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Hector,
If the pellet leaves the barrel at 800 fps, what is the approximate speed of the "propelling pressure wave"?
Thanks,
Yogi
Yogi
Point speeds have been measured, using Schlieren photography, to exceed the 1,100 fps.
Of course, as soon as the air escapes out of the barrel, the inertia of the atmospheric air is enough to create a "mushroom" that mushroom goes in front of the pellet as a highly turbulent flow.
Pellet has to travel through this "soup" unless some mechanical means are used to take the mushroom away from the pellet path.
That is the use of air strippers and well designed moderators.
When you use a FLAT crown (like the dished Match I showed), you are introducing a normal, initial angle to the mushroom, and so the spread is maximized, and the length is minimized. However, it is not reliable to cut flat crowns with hand tools, so the 11 degree crown is the maximum rake you should use in airguns. All our limited run guns had a Flat Dished Match crown put in the barrel by L-W.
Factories IN GENERAL, use a 30 to 45 degrees cutter with a flat face cut for the barrel, cheap, fast and easy. That is good for plinking, but not for high performance guns.
Hope this clarifies the idea.
Keep well and shoot straight!
HM
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Thank you , it does!
I knew that the "mushroom blast" got to the sides of the pellet, I did not know that it got in front of the pellet too.
Would a ported barrel help?
-Y
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Thank you , it does!
I knew that the "mushroom blast" got to the sides of the pellet, I did not know that it got in front of the pellet too.
Would a ported barrel help?
-Y
I think this is why my HW80K .22 is supremely accurate compared to my other HW80s.
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Yogi and John;
Yes and yes.
Problem with airguns when trying to port a barrel is that the pellet''s skirt is STILL under a bit of pressure when it reaches the muzzle. Lead shaving is a very real possibility unless the porting is done with EDM and a VERY slight FORWARD rake. This reduces the pressure behind the skirt before the skirt hits the next leading edge.
Sophisticated airguns have two or three ports with varying degrees of rake, from zero on the first to about 5 degrees on the 3rd.
Of course we are talking of $2-3k airguns.
The "can", if properly designed, will reduce the turbulence in front of the pellet and also act as a harmonics tuner. Especially the English Non-Reflex typical design that uses two or more springs. It is "supremely accurate" within offhand shooting parameters, but it cannot compete under supported shooting competition. Not that that matters to you, I am just laying out my findings for everyone here.
Keep well and shoot straight!
HM
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Yogi and John;
Yes and yes.
Problem with airguns when trying to port a barrel is that the pellet''s skirt is STILL under a bit of pressure when it reaches the muzzle. Lead shaving is a very real possibility unless the porting is done with EDM and a VERY slight FORWARD rake. This reduces the pressure behind the skirt before the skirt hits the next leading edge.
Sophisticated airguns have two or three ports with varying degrees of rake, from zero on the first to about 5 degrees on the 3rd.
Of course we are talking of $2-3k airguns.
The "can", if properly designed, will reduce the turbulence in front of the pellet and also act as a harmonics tuner. Especially the English Non-Reflex typical design that uses two or more springs. It is "supremely accurate" within offhand shooting parameters, but it cannot compete under supported shooting competition. Not that that matters to you, I am just laying out my findings for everyone here.
Keep well and shoot straight!
HM
I was sort of slow to admit the value of the muzzle suppressor as a way to accurize your rifle, mostly because to me the noise of a PCP needs moderation. I had a "reflux" moderator on the .22 FX Tarantula I bought from SS years back which suppressed the sound beautifully! I always wondered why those reflex moderators for air rifles never took on back then but it really worked and since the Tarantula came to me with the Moderator I had no way to figure accuracy comparisons.
It was already accurate.
This springer HW80K with the moderator concerned me somewhat, I was thinking why silence a springer, and most use them for looks or a grab handle for the barrel. So as shots go by I get the sense the rifle is accurate, more accurate than I can say an off hand held springer has ever done for me=I know it's a happy story and I posted what I've been doing "Airgun Related" about this rifle's THIRD style of pellet, JSB Exact, is shooting to the same place as the HN Silhouette Targets, as is the FTT's and the Piranhas.
So now I'm a believer in harmonics and quieting turbulence behind and around an escaping pellet for the best accuracy.
However, there is the unnoticed addition of muzzle blast Suppression that can't really be noticed except by bystanders. So the noise reduction is there as well.
As I understand what the Tarantula had as a suppressor, inside was a spring and a washer with baffles allowing the spring to compress as the fast air escaped the muzzle, giving a recoiless "back springing washer" to delay the gases and pack them or scatter them behind or along the sides instead of getting in front of the pellet.
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Second part in our four part study and exploration:
https://www.ctcustomairguns.com/hectors-airgun-blog/the-saga-of-a-56-th4603110 (https://www.ctcustomairguns.com/hectors-airgun-blog/the-saga-of-a-56-th4603110)
Hope you enjoy!
Part 3 will deal with the differences between the two main current "philosophies" for design of internal powerplants, and in Part 4 I will comment on some further ideas and extensions.
So, stay tuned!
HM
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Hector,
I hope that one section will deal with the centered in comp tube port and the offset transfer port in comp tube. I have always thought the the difference would be a big deal.
I will wait till the series if completed to read it. Some people binge watch TV, I binge read, lol. :D
Hard to shoot straight in an earthquake,
-Y
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Second part in our four part study and exploration:
https://www.ctcustomairguns.com/hectors-airgun-blog/the-saga-of-a-56-th4603110 (https://www.ctcustomairguns.com/hectors-airgun-blog/the-saga-of-a-56-th4603110)
Hope you enjoy!
Part 3 will deal with the differences between the two main current "philosophies" for design of internal powerplants, and in Part 4 I will comment on some further ideas and extensions.
So, stay tuned!
HM
Very cool analysis. In my mind it proves that a rifle is often more than the sum of its parts, with stock, power plant, barrel and trigger unit all interplaying with each other to produce a humbling number of configurations. Optimizing it all can be a challenge or a nightmare, depending on the predilections of the tuner/user.
-Marty
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Hector,
I hope that one section will deal with the centered in comp tube port and the offset transfer port in comp tube. I have always thought the the difference would be a big deal.
I will wait till the series if completed to read it. Some people binge watch TV, I binge read, lol. :D
Hard to shoot straight in an earthquake,
-Y
Yogi;
Sorry to say that no, it will not. The two different philosophies I am talking about is the "full sized" (25 mm's and up) compression chamber bore, and the "skinny piston" (22 mm's and under) sleeved compression chambers.
To talk about what you are suggesting, we would need to do a comparative analysis of a D34, a Walther LGV, and a Walther LGU. We would need to source as identical as possible rifles to establish, given the same powerplants and pellets, the effects of:
1) a diagonally drilled TP that, while longer, IS centered on both ends;
2) a horizontal, short as possible, TP, that is offset on the compression cylinder but central to the bore; and
3) a concentric / coaxial TP-Piston-Compression chamber-Bore,
arrangements.
Perhaps someone can volunteer?
;-)
Keep well and shoot straight!
HM
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Very cool analysis. In my mind it proves that a rifle is often more than the sum of its parts, with stock, power plant, barrel and trigger unit all interplaying with each other to produce a humbling number of configurations. Optimizing it all can be a challenge or a nightmare, depending on the predilections of the tuner/user.
-Marty
Well said. What I've learned so far is that I am never going to sell the few guns I've bought that seem to be perfectly tuned and shoot beautifully, because whatever combination of skill, black magic, and luck that went into making them can be very hard to duplicate!
So far, I have found this to be fascinating, albeit, a bit overwhelming, but very cool nonetheless. Thanks, Hector!
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Very cool analysis. In my mind it proves that a rifle is often more than the sum of its parts, with stock, power plant, barrel and trigger unit all interplaying with each other to produce a humbling number of configurations. Optimizing it all can be a challenge or a nightmare, depending on the predilections of the tuner/user.
-Marty
You are absolutely right, Marty.
What I hope to illustrate with the exercise is that changing ONE thing at a time will give users a feeling for what influences what and how much, and therefore, the time spent in orderly, properly documented, and systematic experimentation, can save the huge headaches of everything going awry...
Thanks for reading and your very well put comments.
HM
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Not sure where I should ask this question so I'll start here.
The theory of the soft bedding has been discussed else where but in actuality the 54 with it's rubber washers is soft bedded yet with changing out those rubber washers you have proven a more solid bedding is more consistent.
Hector where can one get the cone style replacement washers /spacers used in this project?
Also can one use flat washers instead?
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Not sure where I should ask this question so I'll start here.
The theory of the soft bedding has been discussed else where but in actuality the 54 with it's rubber washers is soft bedded yet with changing out those rubber washers you have proven a more solid bedding is more consistent.
Hector where can one get the cone style replacement washers /spacers used in this project?
Also can one use flat washers instead?
Rodger;
The idea of the self-leveling washers is that small variations in humidity of the stock will have less effect when you travel if there is a way to keep the sled-pins in line even with a small stock warpage.
So, the solid bedding has proven more repeatable, specially from assembly to assembly, but in Steve's opinion, the shot cycle is better/smoother with the OEM arrangement AND it added one more aspect he could "tune".
If you want a set of self-leveling washers, I will take one next Monday night.
Keep well and shoot straight!
HM
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Part 3 of the DIANA T/H 56 SAGA
Where we explore the physical differences between the 22 mm's and the 28 mm's powerplants.
Has been posted here:
https://www.ctcustomairguns.com/hectors-airgun-blog/the-saga-of-a-56-th8042880 (https://www.ctcustomairguns.com/hectors-airgun-blog/the-saga-of-a-56-th8042880)
Hope you enjoy!
HM
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It seems to be taking me to prefer the smaller diameter power plant with the larger diameter release outlet.
Or am I seeing something different?
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I find this testing/tuning to be very enlightening and informative for sure. I have followed Steve's threads and tuning with the 22mm kits as well as tuned my own TX and B40 with the 22mm kits. So the actual harmonics and frequencies shown in these reports are even more convincing as to why my FT scores with my TX seemed to increase by about 25 to 30% after my installation of the 22mm kit in the TX as well as the B40 scores.
I can see where the HD does a very good job of settling the barrel harmonics with both kits a great deal for sure. It does seem that the lower amplitude of the 22mm kit is a better solution overall even if the frequency is at a faster rate.
I do not have a D54 to compare to for any extended time but have shot some of friends at matches and like the platform but for me the weight is just more than I care to deal with even though the TX is no lightweight on it own.
My TX is shooting AA 7.87s at 815 fps for 11.61 fpe and is so smooth I can wartch the pellet all the way to the target most shots if the lighting is right. I will never go back to the factory pistons in either the TX or B40.
BD
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It seems to be taking me to prefer the smaller diameter power plant with the larger diameter release outlet.
Or am I seeing something different?
Sure looks like it. I think this implies an inverse relationship between piston mass and TP diameter or between compression volume and TP diameter...
I wonder if this has to do with the need to prevent piston bounce or if it’s to provide quicker transfer of energy to the pellet. Either one should improve efficiency, yes?
-Marty
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been great stuff so far!!!
off to read part 3
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It seems to be taking me to prefer the smaller diameter power plant with the larger diameter release outlet.
Or am I seeing something different?
Sure looks like it. I think this implies an inverse relationship between piston mass and TP diameter or between compression volume and TP diameter...
I wonder if this has to do with the need to prevent piston bounce or if it’s to provide quicker transfer of energy to the pellet. Either one should improve efficiency, yes?
-Marty
Marty, In both of my 56’s I’ve tested the 22mm x 96mm powerplant with TP’s going from the factory 4.1mm down to about 3mm. My experience shows the best performance was observed when using the factory TP size (4.1mm) 👍
Steve
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Yogi;
Sorry to say that no, it will not. The two different philosophies I am talking about is the "full sized" (25 mm's and up) compression chamber bore, and the "skinny piston" (22 mm's and under) sleeved compression chambers.
To talk about what you are suggesting, we would need to do a comparative analysis of a D34, a Walther LGV, and a Walther LGU. We would need to source as identical as possible rifles to establish, given the same powerplants and pellets, the effects of:
1) a diagonally drilled TP that, while longer, IS centered on both ends;
2) a horizontal, short as possible, TP, that is offset on the compression cylinder but central to the bore; and
3) a concentric / coaxial TP-Piston-Compression chamber-Bore,
arrangements.
Perhaps someone can volunteer?
;-)
Keep well and shoot straight!
HM
Hey Marty,
Looks like you have most of the guns mentioned. How about volunteering in the name of science and airgun advancement?
Please, baby, please....
Chocolate Sunday with a cherry on top, AND whipped cream. ;)
-Y
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Hey Marty,
Looks like you have most of the guns mentioned. How about volunteering in the name of science and airgun advancement?
Please, baby, please....
Chocolate Sunday with a cherry on top, AND whipped cream. ;)
-Y
Oh, I didn't realize Hector's wink was directed at me because the LGV and LGU I have are in different calibers... Hector what does "volunteering" entail?
-Marty
(https://gifimage.net/wp-content/uploads/2017/08/who-me-gif-24.gif)
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Oh, I didn't realize Hector's wink was directed at me because the LGV and LGU I have are in different calibers... Hector what does "volunteering" entail?
-Marty
(https://gifimage.net/wp-content/uploads/2017/08/who-me-gif-24.gif)
Nope!
My wink was directed at Yogi.
But he is good at attention diverting, LOL!
HM
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Oh, I didn't realize Hector's wink was directed at me because the LGV and LGU I have are in different calibers... Hector what does "volunteering" entail?
-Marty
Nope!
My wink was directed at Yogi.
But he is good at attention diverting, LOL!
HM
Yogi, you heard the man!
-Marty
(https://media.giphy.com/media/aqYZmnZwfvTmo/source.gif)
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I am glad you all are liking the entries and are enjoying Steve's efforts. I must say it has been a pleasure and a privilege to work with him on this. We may not agree all the time, but when we don't, we agree to disagree and that is very valuable.
I am a bit busy, so I will need a day or two to write the "Epilogue" as all "FBI in Action" programs, this one will have an Epilogue.
But I will address, even superficially, some points here already made:
@ John: What you say is true at about 12 ft-lbs. And I do not think you are a 12 ft-lbs shooter, LOL!
@ Mike: You are inferring things we can only measure in very limited ways and that in these results, so far, may be hidden by other aspects not yet discussed.
I agree that it SEEMS that the 22 mm's kits are producing less harmonics, but another measurement demonstrates that they produce more ENERGY in the harmonics they produce. We'll discuss that in Part 4.
I cannot speak for the TX and HW platforms since until very recently I received my first TX200. I am sure that the 22 mm's kits make those guns more SHOOTABLE, and that undoubtedly reflects on the individual's scores.
Sadly two FT Team USA had severe difficulties with their 22 mm's kits in England (2019 WFTC's). A one day match is not the same as a three day World's. And not every scope that is FT worthy is as robust and reliable as the SWFS SS's that Steve uses.
What these tests DO show, is that the BEST result was obtained with the 28 mm's piston, and that the difference in the OVERALL average performance between the two systems is less than 1/5th of a pellet diameter. The ease of adjusting the HT makes the change of pellet batch, or even an altogether different pellet, to be a simple tuning session and making it possible to tune to the same MV.
@Marty: I've seen people trying equations to relate these variables. In reality it takes one TP size for each piston momentum/pellet energy relation for each caliber.
Too small a TP and you get piston bounce
Too little and you get piston slam and low energy
It's a BALANCE.
I use 5 TP sizes in my builds, and that is just using ONE piston mass. Change that and everything changes.
Overall, it's been a most pleasant experience and I am sure that it has opened new avenues for further work and development.
Thanks to all for reading!
HM
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Not sure where I should ask this question so I'll start here.
The theory of the soft bedding has been discussed else where but in actuality the 54 with it's rubber washers is soft bedded yet with changing out those rubber washers you have proven a more solid bedding is more consistent.
Hector where can one get the cone style replacement washers /spacers used in this project?
Also can one use flat washers instead?
Rodger;
The idea of the self-leveling washers is that small variations in humidity of the stock will have less effect when you travel if there is a way to keep the sled-pins in line even with a small stock warpage.
So, the solid bedding has proven more repeatable, specially from assembly to assembly, but in Steve's opinion, the shot cycle is better/smoother with the OEM arrangement AND it added one more aspect he could "tune".
If you want a set of self-leveling washers, I will take one next Monday night.
Keep well and shoot straight!
HM
Thanks Hector it would be appreciated. I'm also sending you a PM.
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Hector, I agree with all you stated and to be honest I am still just crawling when it comes to understanding all the idiosyncrasies and relationships between all the variables involved in spring guns much less other platforms for sure. I was not aware that there were issues experienced in the worlds with 22mm kits by some shooters but I do understand that a one day match is far less difficult to achieve good results than three days in a row under varying conditions.
Both my TX and B40 have older hawke varmint scopes on them in the 2.5x10x44 version and the UKHFT game we shoot now does not allow for any scope adjustments during a match so once the scope is set to the power and parallax desired for each match it is not touched again. I am not sure if this has any real affect on scope life or performance but my varmints have held up well for several years now with both the factory kits and the 22mm kits in them. In both 15 fpe tunes and 12 fpe tunes. I have read that the 22mm kits are harder on scopes but have not experienced that issue myself, I do know my D48 broke two varmint scopes back to back with a vortek PG2 SHO kit in it and therefore was detuned to 12fpe.
BD
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Hector, I agree with all you stated and to be honest I am still just crawling when it comes to understanding all the idiosyncrasies and relationships between all the variables involved in spring guns much less other platforms for sure. I was not aware that there were issues experienced in the worlds with 22mm kits by some shooters but I do understand that a one day match is far less difficult to achieve good results than three days in a row under varying conditions.
Both my TX and B40 have older hawke varmint scopes on them in the 2.5x10x44 version and the UKHFT game we shoot now does not allow for any scope adjustments during a match so once the scope is set to the power and parallax desired for each match it is not touched again. I am not sure if this has any real affect on scope life or performance but my varmints have held up well for several years now with both the factory kits and the 22mm kits in them. In both 15 fpe tunes and 12 fpe tunes. I have read that the 22mm kits are harder on scopes but have not experienced that issue myself, I do know my D48 broke two varmint scopes back to back with a vortek PG2 SHO kit in it and therefore was detuned to 12fpe.
BD
You are absolutely correct, Mike.
As long as you do not "click" the harmonics energy that the 22 mm's kits produce will not affect you.
As a matter of fact, not clicking the scope is the solution advanced by Tony Leach himself. We had a good, long, conversation while at the 2019 WFTC's
I do not click, long story, too many years of shooting with "cluttered" scopes, LOL!
But the majority of WFTF shooters, do click. And so, without knowing that, it was a guessing ¿What's wrong with my shooting? game. Sadly, the WFTC's is not the place to guess.
Hawkes are not particularly reliable scopes. After, at least, 4 instances of severe issues and one refusal to sustain the warranty, I NEVER use them.
Spring-Piston Airguns are jealous mistresses, if you even look at another airgun, they will slap you in the face with a flyer, LOL!
Yes they are complicated, but the idea behind solid, scientific, testing is to start understanding all the interconnections between the components, and Steve did an admirable job at making sure everything was stable and performing consistently, and then changing just ONE thing.
We'll go into that in Part 4.
Thanks for reading!
HM
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Yes the WFTC's are not the place to be guessing as to why your game is suddenly off the norm is not good at all.
I do agree that hawke scopes are not particularly robust in 1" versions but the two my D48 broke were replaced promptly with no push back, although it was 3 to 4 years ago. Actually one my second returned scope I was contacted and given an option to upgrade from the 1" varmint to a 3x12x50 AMX 30mm sf scope for only 80 bucks and I gladly accepted. I was also informed that while they would stand behind the 1" scope warranties their recommendation for spring guns is to use the 30mm scopes instead. So for me at least I have not had your issues and can say for sure if they do treat me the same in the future they will also lose my business.
Yep spring guns are indeed jealous mistresses. ;) My 124 is one such mistress with regards to scopes. shooting one holers and all of a sudden the reticle falls out of place in erector tubes, granted I do not use high dollar scopes on her for just that reason.
Looking forward to part 4 as well.
BD
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Hector, I agree with all you stated and to be honest I am still just crawling when it comes to understanding all the idiosyncrasies and relationships between all the variables involved in spring guns much less other platforms for sure. I was not aware that there were issues experienced in the worlds with 22mm kits by some shooters but I do understand that a one day match is far less difficult to achieve good results than three days in a row under varying conditions.
Both my TX and B40 have older hawke varmint scopes on them in the 2.5x10x44 version and the UKHFT game we shoot now does not allow for any scope adjustments during a match so once the scope is set to the power and parallax desired for each match it is not touched again. I am not sure if this has any real affect on scope life or performance but my varmints have held up well for several years now with both the factory kits and the 22mm kits in them. In both 15 fpe tunes and 12 fpe tunes. I have read that the 22mm kits are harder on scopes but have not experienced that issue myself, I do know my D48 broke two varmint scopes back to back with a vortek PG2 SHO kit in it and therefore was detuned to 12fpe.
BD
You are absolutely correct, Mike.
As long as you do not "click" the harmonics energy that the 22 mm's kits produce will not affect you.
As a matter of fact, not clicking the scope is the solution advanced by Tony Leach himself. We had a good, long, conversation while at the 2019 WFTC's
I do not click, long story, too many years of shooting with "cluttered" scopes, LOL!
But the majority of WFTF shooters, do click. And so, without knowing that, it was a guessing ¿What's wrong with my shooting? game. Sadly, the WFTC's is not the place to guess.
Hawkes are not particularly reliable scopes. After, at least, 4 instances of severe issues and one refusal to sustain the warranty, I NEVER use them.
Spring-Piston Airguns are jealous mistresses, if you even look at another airgun, they will slap you in the face with a flyer, LOL!
Yes they are complicated, but the idea behind solid, scientific, testing is to start understanding all the interconnections between the components, and Steve did an admirable job at making sure everything was stable and performing consistently, and then changing just ONE thing.
We'll go into that in Part 4.
Thanks for reading!
HM
..."Spring-Piston Airguns are jealous mistresses, if you even look at another airgun, they will slap you in the face with a flyer, LOL!..."
HA HA! Boy are you not joking! I've been shooting all my other "hunting" springers while my .22 HW80K has been resting! And what these rifles are doing to me to make me spend MORE time with THEM!
I got out my .20 97K-T and sighted it in to hit with an OLD scope, the Leu VXII 3-9X 33mm from decades ago, and it's doing nice but it DOESN'T do what my HW80 .20 DOES after it! With HEAVIES.
Then I pumped back the Beeman Falcon .25 to 195 BAR and put JSB KING in there and it still shoots exactly where it's pointed using a BugBuster 4-12X.
Now I feel the NEED to go back and pull out the HW80K .22 to let it know I NEVER FORGET! ;D
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Part 4 has been published:
https://www.ctcustomairguns.com/hectors-airgun-blog/the-saga-of-a-56-th2541108 (https://www.ctcustomairguns.com/hectors-airgun-blog/the-saga-of-a-56-th2541108)
Sorry for the delay, but there's been so much advance in the "aftermath" that I think we will need to put out two or more really serious entries.
Anyway, I hope you enjoy!
HM
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Part 4 has been published:
https://www.ctcustomairguns.com/hectors-airgun-blog/the-saga-of-a-56-th2541108 (https://www.ctcustomairguns.com/hectors-airgun-blog/the-saga-of-a-56-th2541108)
Sorry for the delay, but there's been so much advance in the "aftermath" that I think we will need to put out two or more really serious entries.
Anyway, I hope you enjoy!
HM
Thanks Hector for the link. You said in the blog the tuner would be available as an after market add on but there would need to be some gunsmithing to put one on a TO1 ? My TO6 48 Barrel and the TO1 54 barrel look the same with the front sight removed so maybe you can expand on the comment.
Thanks
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Thanks Hector for the link. You said in the blog the tuner would be available as an after market add on but there would need to be some gunsmithing to put one on a TO1 ? My TO6 48 Barrel and the TO1 54 barrel look the same with the front sight removed so maybe you can expand on the comment.
Thanks
They should not!
T01 rifles had a metallic muzzle piece that aligned with the barrel's "Vertical" using two dovetails at the top of the barrel itself.
T05 and T06 rifles have a slant cut at the muzzle end and a corresponding slant in the plastic piece that aligns the verticality of the front sight.
If my suggestions were heeded, that slant is no longer there (a reduction in production costs), and the HPM is completely cylindrical, as there is no need to align anything. But if the barrels have the slant, then a small hollow will be there, but if the barrels had the dovetails, then they will need careful filing off of the RAISED portions of the dovetails. Do NOT eliminate the dovetails, very little filing will be required to obtain a snug fit.
Hope this clarifies the situation.
HM
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Thanks Hector for the link. You said in the blog the tuner would be available as an after market add on but there would need to be some gunsmithing to put one on a TO1 ? My TO6 48 Barrel and the TO1 54 barrel look the same with the front sight removed so maybe you can expand on the comment.
Thanks
They should not!
T01 rifles had a metallic muzzle piece that aligned with the barrel's "Vertical" using two dovetails at the top of the barrel itself.
T05 and T06 rifles have a slant cut at the muzzle end and a corresponding slant in the plastic piece that aligns the verticality of the front sight.
If my suggestions were heeded, that slant is no longer there (a reduction in production costs), and the HPM is completely cylindrical, as there is no need to align anything. But if the barrels have the slant, then a small hollow will be there, but if the barrels had the dovetails, then they will need careful filing off of the RAISED portions of the dovetails. Do NOT eliminate the dovetails, very little filing will be required to obtain a snug fit.
Hope this clarifies the situation.
HM
Thanks for the reply Hector.
The birth date on the rifle is August 2001 and I've had the front sight off so it diffenetly has the slant machined on the barrel. Maybe they ran out of barrels when changing over to the TO5.
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I'm unaware of the second person on the team who had issues with their 22mm setup. The only one I know of would be Matt.
Matt TX200 w/ 22mm
Leo LGU
Ray D54
Jay HW97
Nathan LGU
And me TX200 w/ 22mm.
Even though I was the lowest scoring team member I did not have issues with my 22mm kit, and luckily never have had issues with clicking using one. Lucky? I might be, but I've been successful with using a cheap Tac Vector Scopes at the price of $200, and my newest scope Falcon X50 which I had mounted on my 22mm TX in England.
My issues were almost all mental and also had visibility issues. To my knowledge nothing to do with the gun and it's internals.
Besides all that, I've been enjoying the comparisons between the two powerplants. The next test should be dropping these internals into a Diana 48/52. You will most likely see a rise in power/ efficiency in both powerplants having them in a non sliding action won't rob power from the powerplant. The sliding action adds it's own element to the performance of each kit, being that the sled itself no matter how well tuned/ smooth it is can add a variable to the performance and accuracy over time.
Cam
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You will most likely see a rise in power/ efficiency in both powerplants having them in a non sliding action won't rob power from the powerplant.
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Cam
Interesting POV Cameron.
Do keep us posted if you do the tests.
In my experience, holding a spring piston rifle tightly almost always yields lower MV's (therefore lower ME's), while holding them lightly almost always yields higher MV's.
In this sense, the sled system provides the shooter with a uniform and constant "hold". Which can be tuned to be as "tight" or as "loose" as the combination of pellet, barrel, and MV needs. Tuning your own personal "hold" takes a lot more ammo. ;-)
The variability over time can come from many things, but once a sled system is well run in, it shouldn't change much, if at all.
Just the results of a few million rounds fired by a good lot of shooters all over.
Keep well and shoot straight!
HM
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You will most likely see a rise in power/ efficiency in both powerplants having them in a non sliding action won't rob power from the powerplant.
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Cam
Interesting POV Cameron.
Do keep us posted if you do the tests.
In my experience, holding a spring piston rifle tightly almost always yields lower MV's (therefore lower ME's), while holding them lightly almost always yields higher MV's.
In this sense, the sled system provides the shooter with a uniform and constant "hold". Which can be tuned to be as "tight" or as "loose" as the combination of pellet, barrel, and MV needs. Tuning your own personal "hold" takes a lot more ammo. ;-)
The variability over time can come from many things, but once a sled system is well run in, it shouldn't change much, if at all.
Just the results of a few million rounds fired by a good lot of shooters all over.
Keep well and shoot straight!
HM
Hey Hector!
There's no doubt that the builders at the factory are the only people who have had their hands on more Dianas. Maybe this was just a fluke, but when I took my 12fpe setup in my 48 and put it in my 56 (piston, seal, comp tube, spring and quide) I had a loss in power by 2fpe. Then I took one of my homemade 22mm kits at 12fpe and put it in the 56 and it was down as well.
There are many more variables than a sliding action such as the barrel potentially being tighter than others. I have pushed pellets through the three that were on the bench that day and while my arm hasn't been calibrated by my local weights and measures office they all felt very close. I just assumed the whole equal and opposite reaction robbed power. Which I'm sure is true, but I'm unsure as to what percentage. I'd personally be Interested to see if you had a similar experience!
Cam
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This reminds me of the Browning Boss:
https://www.browning.com/support/frequently-asked-questions/boss-system.html (https://www.browning.com/support/frequently-asked-questions/boss-system.html)
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This reminds me of the Browning Boss:
https://www.browning.com/support/frequently-asked-questions/boss-system.html (https://www.browning.com/support/frequently-asked-questions/boss-system.html)
Yes, and No.
The airgun equivalent of the Boss was the Vortek Muzzle Tamer (VMT).
Fine threads, adjustable weight, marks for "reproducibility" .
I used one for a couple of years.
In airguns, ANYTHING that is adjustable, WILL get out of "adjustment" at the WORST POSSIBLE TIME", and for me the last straw, was the WFTC's in Lithuania.
By the time I had discovered and fixed the wandering weight of the VMT, the 3 day Match was over.
What I decided then was to try a weight and started shaving weight by cuts of 0.005" till I found the right weight for 12 ft-lbs, which I found was not the right weight for 20 ft-lbs. So, I determined THAT weight also.
Recently, a friend who is truly a vibrations professional came up with an interesting comment and I developed the next generation, that is a Harmonics REDUCER, and it works, but it is extremely expensive to make (9 precision parts). And so the decision with DIANA was to offer the much simpler HT/HPM.
Why does the HPM cannot get out of adjustment? Because the forward recoil of the guns actually settles the HPM in place EVERY TIME you shoot. The ORings that are used as "spacers" can be had in two hardnesses and, actually, tests have proven that using two hardnesses actually allows finer adjustments than the 1.5 mm's - "set" that the original spec called for. There are no threads to lock, no fine lock nuts to jam. Add or delete ORings and the spacing will change. Settle the gun with three shots and see what the gun is doing. The repeat till you are happy.
What the Boss document refers to benchrest reloaders developing special loads is what we do when we change the spring and add or remove spacers.
Our barrels are MUCH slenderer than the powderburner's, and yet the proportion of mechanical energy / lateral vibrations to stiffness in the spring-piston airgun exceeds that of a powderburner that adds to the stiffness of the barrel metal and diameters the enormous pressures that "stiffen" the barrel like an inflated sausage balloon.
The original spec of the HPM called for 6 screws to hold it in place, and I am afraid that in the end, DIANA uses 1 (we're still exchanging EMails about it), but that is an easily solvable problem even with hand tools. The main thing is that the users can START with the right approach.
Keep well and shoot straight!
HM
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Hey Hector!
There's no doubt that the builders at the factory are the only people who have had their hands on more Dianas. Maybe this was just a fluke, but when I took my 12fpe setup in my 48 and put it in my 56 (piston, seal, comp tube, spring and quide) I had a loss in power by 2fpe. Then I took one of my homemade 22mm kits at 12fpe and put it in the 56 and it was down as well.
There are many more variables than a sliding action such as the barrel potentially being tighter than others. I have pushed pellets through the three that were on the bench that day and while my arm hasn't been calibrated by my local weights and measures office they all felt very close. I just assumed the whole equal and opposite reaction robbed power. Which I'm sure is true, but I'm unsure as to what percentage. I'd personally be Interested to see if you had a similar experience!
Cam
Hello Cameron!
Yes there are a ton of aspects that determine the "efficiency" of a powerplant from beginning to end. That was one of the LENGTHY discussions we had with Steve. In the end, we decided we did not want to detract from the basic concept of the article.
We ARE working in some way to analyze things cooly and objectively. We/I will undoubtedly post something in depth in a few weeks. With the same spirit, to post facts, and just facts.
Now, to your experience:
A too loose barrel (like most 56's, for example, they prefer 4.53 pellets) will create a loss of energy.
The fit between the two "cones" in the respective breeches are also different (the 56's are much more flat faced than the 48's), and that will create a loss of energy (as is often the case in the 430L).
And there are other factors.
BUT, a test you can do EASILY with just a gun and a chrono:
Shoot a 5 shot string with the "artillery" hold, and shoot a 5 shot string holding the gun like you would a 0.308" Win hunting gun. In almost all cases, I have found that a tight hold will produce LOWER ME's.
Guns in which I have experienced this:
D48
Walther LGU
Walther LGV (original piston)
TX-200 (I finally got one, LOL!)
FWB 124 (old version, but powered up by a PA tuner)
Mauser AM03 (traditional piston, NOT the ABP)
HW95 (my wife's "engagement rifle")
An HW97 that a friend asked me to tune for him, a blue stock/electroless nickel action specimen of uncommon beauty.
The ONLY guns I have NOT found this to be true are the ones equipped with an ABP, and those that are remarkably underpowered for their weight (which makes sense), like the old 10 M Match guns.
So, that is the extent of my experience. In SOME CASES, the difference has been a few FPS (3-7), in others it has been not more than 20 fps, but never 2 full ft-lbs.
It would be interesting to look at your tests in detail.
Just to finish off this post, I would like to point out (as I emphasized in the Epilogue) that the post was NOT intended as a 22 vs. 28 comparison (I've clarified in other posts that I am no longer interested in discussing that), it was intended to prove that for TWO VASTLY DIFFERENT POWER-PLANTS, the HT concept works. Perhaps more, perhaps less, but it works on both, and therefore, by the law of natural continuity (only suspended in Quantum environments), it should work in every other powerplant.
Thanks for reading, and for taking the time to comment.
I will miss you in SouthAfrica, but I fully understand the current predicament, having two little ones myself (3 and 4 YO's).
Keep well, give my best to Jessica and to her parents, that are a blast; and let us know how everything is going.
HM
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22mm and scopes.
I have sold over 300 TX kits now, 2 people have come to me with possible scope issues, one the gun/scope works and then does not then does then does not, i try my best to help the gent but i have no clue what else to suggest as i feel there is little to no issue, the other is Matt, a shooter at the worlds who Hector is talking about. For the record i feel Matt has something else going on, nothing wrong with the tune on his gun and here is why.
22mm TX's produce way less surge and recoil on the actions, how do i know this? years ago it was measured, the gun was 23mm but the results are very close. A gent in the UK built an airgun test rig that clamped where the scope sits, the unit measured surge/recoil etc, also data recorded the moment the pellet leaves the muzzle so true locktime can be recorded also. My rifles were compared to others, at that time the gent doing the data collection commented he had no idea how it was done but the small piston guns were quite awesome.
Also one of my kits has been tested on the Airgunforum here in the uk more recently, it again shows reduced recoil and surge. So now lets chat about Danny, a mate of mine who like Steve had a Diana 56, this 56 had 28mm. 22mm, 20mm tunes and was sold with 25mm tune, he sold it 25mm as we had an issue taming power with 20mm ::) he now regrets selling the gun as it was so accurate (think 12mm 10 shot group at 80 yards running 11fpe+ shoting JSB express outdoors) This 56 was incredible, and lucky for us Danny shot video with a scope cam with 28mm and small piston conversion, 28mm destroyed the camera image totally, the small piston conversion allows the pellet to be seen flying shortly after leaving the barrel and just missing the target, this gun was pushing 800fps + with 7.9s and yet you can watch pellets fly on a scope cam and the scope recoils back with the gun on a sled!! Incredible.
So, 22 ,21 or 20mm tunes, bad for scopes? I feel they are no more harsh/dangerous than .22 rimfire, i think recoil sleds are harsh on scopes, i think scopes can wear, i think rifles dovetails can wear as can risers and i feel this has all gotten out of hand with basically opinions being taken as fact. If 22mm killed scopes, Myself, Jon Budd, NickG, Cameron, Bruno Silva and many others would be inundated with owners complaining their scopes were dying on their rigs, the fact is they are not. I have sold over 300 TX kits and converted over 50 Diana rifles now, 20+ HW97 and 77's too, sure there will be the odd one or 2 with issues, and i do my best to help, BUT i resent this notion that 22mm is bad on scopes, it could even be softer imo.
So 2 people with scope issues, both personally i feel are not down to the tune within the gun, more the scopes being worn or other issues with mounts etc, zero other complaints. I have people winning competitions, providing me feedback they are loving the guns now, find them so much easier to shoot, watching pellets fly, watching where the wind is taking the pellets at target so they can essentially allow for the wind so much easier on the next shot, all this made possible as the scopes are now barely moving at all!
So by the shear number of none complaints about scopes and 22mm i get...i feel its a none issue. Scopes do wear though, people often forget that point.
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To add to this, Optisan are about to launch 2 new HFT scopes, one is already announced being 3-12x32 side focus etc. Optisan spent a long time on this cope beefing up the side parallax/turrets etc to cope with the abuse a springer will inflict on it, its a scope specifically built to withstand recoil and surge. That said it will work on much anything else as a scope that survives a springer can survive easy on most firearms also. The prototypes have been shot near a year in the UK on rifles with my kits installed...no issues at all ;) Many FT scopes are not that good on springers, they are more built for PCP rifles, it pays to choose well what FT scope you choose to use on a springer.
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Tony any chance that you will do a kit for break barrels? HW 50's and 95's in particular.
Thanks,
-Yogi
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No scope issues with either my B40 or TX 22mm kits with 150 buck Hawke varmint 1" scopes mounted to them. I can say the 22mm kits increased my HFT scores by 25 to 30% easily by just the reduced recoil and consistent velocities from the power plants.
I am a happy camper. ;D ;D
BD
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Just to echo what buldawg said, no scope issues on my 22mm TX too. It's had a sidewinder 30, an mtc viper connect and an ole reliable 1 inch tube vantage, (my very oldest scope). The vantage is still going strong on the 22mm TX. Although, I haven't really been shooting the TX that much due to a sweet shooting D52 that also has Tony's 22mm piston. The 52 has a Mamba Lite that's not really known as a magnum rated scope like say an Airmax 30 but the Mamba is also going strong. But just wondering, I'm no expert but shouldn't these 150 gram-ish pistons and softer springs in these kits actually produce less recoil/shock that could harm scopes? The shot cycle seems indicate that there's less recoil going on. Guess we won't know for sure unless someone has an accelerometer and some spare time out there but yeah, shouldn't light piston = less recoil?
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Hi HM,
Now that is an very educating write up!
Ot wil take a couple of hours (weeks) to give it the right place.
Do you think it is possible that a pellet is out of the barrel before the action starts moving forwards?
Thanks!
Regards, Robert.
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Hi HM,
Now that is an very educating write up!
Ot wil take a couple of hours (weeks) to give it the right place.
Do you think it is possible that a pellet is out of the barrel before the action starts moving forwards?
Thanks!
Regards, Robert.
Hello Robert!
Thanks for your kind words.
According to all the measurements we have done, the pellet takes between 2 and 6 msecs to go from breech to muzzle.
MOST recoiling cycles take between 8 and 16 msecs. And that is without the "Twang".
So, no, I don't THINK that there is a chance of the pellet exiting the muzzle before the piston starts moving backwards, and therefore the action starts moving forwards.
But we will know much more when we have done more accelerometer plots like the one shown in the Epilogue for the ASP20.
Thanks for reading!
HM
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HM,
For me it is not possible yet to place vids, but when you type "diana 56 slomo" on youtube maybe you'll find it.
Done some testing in the past.
Otherwise I will place it myselfe when possible.
Regards Robert.
Edit: I use .22 only ;)
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Deze, Robert?
https://www.youtube.com/watch?v=_MizI8VxUK8 (https://www.youtube.com/watch?v=_MizI8VxUK8)
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Nice video. Clearly the sled starts moving when the Piston does, as would be expected.
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Good video, thanks for posting ;)
Steve
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Thanks Subscriber!
The vid is made with simple and cheap equipment.
Each frame is +- 1/1000 sec.
You see the pellet leaving the barrel after the barrel started moving forwards again, 1 frame.
In that same frame you see the barrel dropping 0,5mm,
I think this is the area where HM's harmonick tune comes in action.
HM, Is the Original weight calculated for more power and is this a straight line compared to energy?
I also made some vids of the piston of an HW97, one can see it in the action while shooting.
Is it corect to state that the piston in a springer airgun NEVER hits the botom of the cilinder at first stroke?
Even whithout a pellet it didn't.
With a properly tuned action the piston comes at rest after the second stroke, most factory stuff takes 3 times.
Regards, Robert.
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I would think that if the piston did not strike the end of the cylinder when fired without a pellet, that would imply the transfer port was very restrictive. This would amount to a serious de-tune, below the power capability of that piston mass, diameter, stroke, spring rate and preload.
If you had higher frame rate videos of a powerful springer being fired with and without a pellet, and the dry fire showed the barrel snapping forwards with higher acceleration than with a pellet, that would be evidence of collision between piston and cylinder end during dry fire. Certainly, the air pressure in front of a dry fired piston should be much lower. Therefore not a very firm "cushion".
Now, there are lots of observations and beliefs on this board that we hold as truth because they seem logical, and no better information is available. If you read threads about shooting pellets that are "too heavy" or "too light", two themes emerge:
Heavy pellets cause excessive piston bounce and reduce pellet energy. This seems to be confirmed by shooting them over chrony. Shooting light pellets results in harshness that is attributed to the piston impacting the end of the compression cylinder. Again, the energy of a light pellet is reduced below that of
the "right weight" pellet. With a light pellet, some of the lost energy goes into impact between piston and cylinder end face.
If these "facts" are true, then dry firing a similar platform must cause a direct piston collision with the end of the cylinder. It is something that if repeated is known to break parts...
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Hector, you are a wealth of knowledge! Thankyou for the good read and info!
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Sorry, Robert, I had not seen your videos before commenting. Based on your HW97 videos (posted below) I would agree with you except for one caveat: Data aliasing.
Due to the slow frame rate and obviously jerky replay, it is possible that the piston traveled further than you can see in the video on the initial stroke. It is just that there were no frames captured to reflect that. When your sampling rate is too slow it is very easy to get aliasing, where there is an appearance of a trend or natural frequency that is actually false. Or to simply fail to capture something that actually happened.
The best example I can give you is this: Watching a short barrel semi-automatic rifle being discharged, with video having too short an exposure, and too slow a frame rate: Some shots show a large fireball from the muzzle while others show nothing. This gives the appearance of large variations in flame, but are really just sampling errors.
So, you may be right; but I would like to see slow motion at a frame rate where the replay is smooth.
Perhaps you could contact these guys and collaborate with them:
https://www.youtube.com/user/destinws2 (https://www.youtube.com/user/destinws2)
https://www.youtube.com/user/theslowmoguys (https://www.youtube.com/user/theslowmoguys)
One other factor that plays a role in piston bounce is the inertia of the rifle (or more exactly; the relative inertia between piston and rifle). A third of rifle inertia is the wood stock. When you remove that, then the compression tube can be pushed forwards and backwards more than if it were attached to the stock. Thus, piston bounce may be exaggerated because the compression tube is pushed out of the way.
In the videos you can see exaggerated recoil of the compression tube due to the lost inertia of the missing stock. So, the piston velocity is reduced from what would be seen with a stock attached. The missing energy being imparted to the compression tube instead. If you brace or attach the compression tube to something heavy or solid, the action you capture will be different. The stock would be idea, but you want to see the cocking slot...
Question: Is this a "full power" HW97?
https://www.youtube.com/watch?v=4WvbxAlLKoc (https://www.youtube.com/watch?v=4WvbxAlLKoc)
https://www.youtube.com/watch?v=Pwu_LJoCoLw (https://www.youtube.com/watch?v=Pwu_LJoCoLw)
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Sorry, Robert, I had not seen your videos before commenting. Based on your HW97 videos (posted below) I would agree with you except for one caveat: Data aliasing.
Due to the slow frame rate and obviously jerky replay, it is possible that the piston traveled further than you can see in the video on the initial stroke. It is just that there were no frames captured to reflect that. When your sampling rate is too slow it is very easy to get aliasing, where there is an appearance of a trend or natural frequency that is actually false. Or to simply fail to capture something that actually happened.
The best example I can give you is this: Watching a short barrel semi-automatic rifle being discharged, with video having too short an exposure, and too slow a frame rate: Some shots show a large fireball from the muzzle while others show nothing. This gives the appearance of large variations in flame, but are really just sampling errors.
So, you may be right; but I would like to see slow motion at a frame rate where the replay is smooth.
Perhaps you could contact these guys and collaborate with them:
https://www.youtube.com/user/destinws2 (https://www.youtube.com/user/destinws2)
https://www.youtube.com/user/theslowmoguys (https://www.youtube.com/user/theslowmoguys)
One other factor that plays a role in piston bounce is the inertia of the rifle (or more exactly; the relative inertia between piston and rifle). A third of rifle inertia is the wood stock. When you remove that, then the compression tube can be pushed forwards and backwards more than if it were attached to the stock. Thus, piston bounce may be exaggerated because the compression tube is pushed out of the way.
In the videos you can see exaggerated recoil of the compression tube due to the lost inertia of the missing stock. So, the piston velocity is reduced from what would be seen with a stock attached. The missing energy being imparted to the compression tube instead. If you brace or attach the compression tube to something heavy or solid, the action you capture will be different. The stock would be idea, but you want to see the cocking slot...
Question: Is this a "full power" HW97?
https://www.youtube.com/watch?v=4WvbxAlLKoc (https://www.youtube.com/watch?v=4WvbxAlLKoc)
https://www.youtube.com/watch?v=Pwu_LJoCoLw (https://www.youtube.com/watch?v=Pwu_LJoCoLw)
Seems to move more with no pellet. Cool stuff! :D
-Y
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Thanks again subscriber!
It is good to know help shows up when needed.
I also understands your thoughts about the vids.
But
When in doubt, I say reproduce.
I made several vids and each one of them showing the piston not reaching the botom at first stroke.
I asumed at least one vid must have showed up when fps and shutter time was in the question.
For xample: the moving barrel vid shows the pellet leaving the barrel.
I got vids showing no pellet, is was just not there.
Then there is the energy question.
How is it possible for the piston to bounce when there is no air left to bounce on?
So
When it smells like fish, taste like fish, looks like fish, it must be something like a fish.
:D
I do not want to take over HM's topic, especialy me being a brand new member.
A forum is there to exchange knowledge and there is so much of it.
Regards, Robert.
This was a 23 joule modified HW97
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@ Robert.- More than MY thread it is really Steve's. He did all the hard work, took the pictures, did the writeups. I only put some effort into planning and then presenting everything. Really the credit goes to Steve.
I am very intrigued by your videos, don't know how many videos you took before being able to capture the streak of the pellet, but it is clear it wasn't easy. On one hand, congrats on the perseverance, on the other, I have often said that repeating the same actions expecting a different outcome is either folly or faith. So, take your pick. ;-)
In general, I do NOT trust videos. Sampling aliasing, as Peter calls it is one reason, the other is that I believe human senses to be totally inadequate for the speeds at which airguns work. If you look at the accelerometer plot in the "Epilogue" of the 56 SAGA, you will note that the smallest scale unit we can show is msecs, but this happens because we have 10 times that resolution in the sampling rate. Otherwise, it would not be metrologically acceptable.
Also I find somewhat peculiar why your 56 goes back, stops, starts moving forward, then pellet exits, then the action still moves further BACK, then another burst of air comes out (0:08 to 0:13).Yes I noticed the special powerplant you are using, and so, this would be my request to you:
The forum is what WE ALL make of it, you raise some VERY important questions and clearly have the time, ability and equipment to throw some light into the matter. SO:
¿Would you be willing to do some videos to make a Blog entry out of them?
We would not "embed" the videos in the blog post, but put links, and I would probably need Peter's help in making a frame by frame analysis. Most probably, you can coordinate among yourselves in Nederlands.
I THINK it would be an interesting collaboration.
You two are very smart persons and I am sure we can achieve an interesting analysis.
Coming now to your questions:
There are THREE weights of HPM: One for the 12 ft-lbs people, one for the 20 ft-lbs people, and one for the 56 people.
It is the COMBINATION of weight AND location what acts as a dampener of the muzzle's oscillations, thereby shifting the loci of the maximum excursions in TIME. By ensuring that the pellet leaves the muzzle more or less when the muzzle is in one of the extremes, where perpendicular movement has come to a max and now starts heading the other way, we ensure that small variations in MV (natural to EVERY airgun) will not affect POI.
Can the piston reach the end of the travel without pellet in the chamber? Yes it can. BUT it would mean a TP that is oversized.
What is happening in the HW97? You can clearly see how the spring has "travelling waves" that raise all sorts of havoc.
When there is no pellet in the chamber it does NOT mean there is no air, and air compressed to enough pressure is just as hard as a solid. A flow of air that needs to flow faster than the speed of sound will obturate rather than allow the flow (unless the temperature is driven high enough) so, even without a pellet, the air that is inside the compression cylinder, given a small enough orifice WILL act as a wall.
What we see in your video is that AFTER the pellet is expelled there is ANOTHER jet of air exiting the barrel therefore you need to see that there IS air in the barrel and in the compression chamber, even after the pellet has exited the muzzle. You have proof of that in YOUR OWN video.
If it smells like fish, poops like a fish, looks like a fish; . . . it could be a politician!
;-)
@ Peter.- Damage does not necessarily demonstrate physical contact between two parts, either a fluid or a supercompressed gas can transmit enough energy to damage parts.
Thanks for your help in this, your frame by frame analysis is brilliant.
See above and let me know if you would like to participate.
@Bladebum.- Thanks!
@ Yogi.- I am still considering your proposal. I just need to find some elements. ;-)
Thanks for reading!
HM
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Hector,
Thank you for your reaction!
I will take your suggestion in mind.
Also I find somewhat peculiar why your 56 goes back, stops, starts moving forward, then pellet exits, then the action still moves further BACK, then another burst of air comes out (0:08 to 0:13).
Looking at the results from the Harmonics Expert,
is your 56 is doing the same?
Regards, Robert.
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Hector,
Thank you for your reaction!
I will take your suggestion in mind.
Also I find somewhat peculiar why your 56 goes back, stops, starts moving forward, then pellet exits, then the action still moves further BACK, then another burst of air comes out (0:08 to 0:13).
Looking at the results from the Harmonics Expert,
is your 56 is doing the same?
Regards, Robert.
I'll need to send the High Speed camera to Steve and let him do the filming.
If you see the (very bad) video here:
https://www.ctcustomairguns.com/hectors-airgun-blog/a-high-speed-analysis-of-the-way-the-zr-mounts-work (https://www.ctcustomairguns.com/hectors-airgun-blog/a-high-speed-analysis-of-the-way-the-zr-mounts-work)
And you look closely at the "fixed" portion of the scope rail in the gun, it would seem that no, the gun doesn't move back further after the first piston strike... But then the video is really bad and it is a full bore, full power, version.
Keep well and shoot straight!
HM
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Hector,
I appreciate that a fluid can act solid, if a collision happens at high enough speed. This is what people experience when they jump off a cliff into the ocean.
Rather than argue if the air pressure is high enough or applied abruptly enough to cause damage when a springer is fired without a pellet, I would just contemplate this: When there is a pellet in the breech, the peak air pressure behind it must be higher than when the same airgun is fired without a pellet, because the pellet acts as a temporary obstruction.
Now, perhaps that peak pressure results in enough adiabatic heating, to then aid the flow through the TP as it is converted to plasma. Perhaps the lower bulk peak air pressure when fired without a pellet reduces the heating of air, to the extent that the air does not behave as a very thin plasma, but as a much more viscous gas. That, in turn acts to restrict flow through the TP, and cushion the piston? This would seem like very clever or very lucky engineering.
Or, it is the air near the OD of the piston seal that has to achieve much higher radial acceleration without a pellet loaded, because of the higher peak piston speed: Just as the piston is about to reach the end of the cylinder, that air might act both as a cushion and as the source of extremely high localized pressure. Damaging then, perhaps a bit like cavitation causes damage, despite insignificant bulk pressure further away from a pressure vessel wall.
If one were to attach accelerometers to the compression cylinder and piston, that data should indicate if the whole mass is involved in a significant collision, or just the contact surfaces.
Generally, I think that higher time resolution instruments would be helpful to ensure nothing is being missed...
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I think the second stroke is doing the damage without pellet.
It slams dead against the botom of the cilinder.
If I posted the whole vid you would see that the spring reaction after that lasts much longer.
So it is bad for the seal and the spring.
I could hear the "tick" of air going through the barrière.
Regards, Robert
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Since the idea of high speed photography is being discussed, has anyone considered running experiments with a compression tube made out of plexiglass? It would allow filming of the piston in action rather than guesstimating it’s dynamics from recoil measurements.
I’m definitely not a material scientist, but perhaps a plexiglass compression tube could be made on a mini-lathe and matched with a regular barrel/breech in a vise. Filming the piston and any associated flash from air combustion would be an amazing experiment. The first guy to do it first could be called (insert deep voice) - The man with the plexiglass gun! - Kind of catchy don’t you think? ;D
-Marty
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Hector,
I appreciate that a fluid can act solid, if a collision happens at high enough speed. This is what people experience when they jump off a cliff into the ocean.
Rather than argue if the air pressure is high enough or applied abruptly enough to cause damage when a springer is fired without a pellet, I would just contemplate this: When there is a pellet in the breech, the peak air pressure behind it must be higher than when the same airgun is fired without a pellet, because the pellet acts as a temporary obstruction.
Now, perhaps that peak pressure results in enough adiabatic heating, to then aid the flow through the TP as it is converted to plasma. Perhaps the lower bulk peak air pressure when fired without a pellet reduces the heating of air, to the extent that the air does not behave as a very thin plasma, but as a much more viscous gas. That, in turn acts to restrict flow through the TP, and cushion the piston? This would seem like very clever or very lucky engineering.
Or, it is the air near the OD of the piston seal that has to achieve much higher radial acceleration without a pellet loaded, because of the higher peak piston speed: Just as the piston is about to reach the end of the cylinder, that air might act both as a cushion and as the source of extremely high localized pressure. Damaging then, perhaps a bit like cavitation causes damage, despite insignificant bulk pressure further away from a pressure vessel wall.
If one were to attach accelerometers to the compression cylinder and piston, that data should indicate if the whole mass is involved in a significant collision, or just the contact surfaces.
Generally, I think that higher time resolution instruments would be helpful to ensure nothing is being missed...
As usual, I think you are absolutely right. AND I would add that BOTH your scenarios are possible and do happen:
Consider that if you seat a pellet too far into the rifling, then MV drops. Meaning that REDUCING the opposing force created by the pellet's inertia and fit into the chamber will ALSO reduce the peak pressure. That is something that we have all experienced (or can easily test).
My experiments with synthetic piston faces led me to believe that the temperature AND the pressure at the compression chamber walls are MUCH higher than at the center. We learned that from the "soot spots" left on the piston's face when I was trying to establish the peak temperature in the compression chamber. So we have reasonable proof of that. IDEALLY, this would mean that the most efficient piston face would have a truncated "aerospike" in the center. Alas this is not industrially possible, though it would have another positive effect: it would reduce the length of the transfer port.
Now, I don't think it was neither lucky, nor clever engineering.
It is simply the result of over 150 YEARS of EVOLUTION of a basic design. We lost the "fuel" when we went from leather seals to synthetic, but we gained pressure and temperature, and UNDERSTANDING of what is happening.
A simple way of testing if one scenario prevails over the other would be to compare the HW97 to the HW95. Virtually the same powerplant, but the 95 is INCAPABLE of transferring plasma through the TP, whereas the 97 is. So, seeing if there is a difference between the pellet/no pellet relation in both powerplants would teach us something.
¿Are you listening Robert? LOL!
Thanks again for your brilliant explanation.
Keep well and shoot straight!
HM
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I think the second stroke is doing the damage without pellet.
It slams dead against the botom of the cilinder.
If I posted the whole vid you would see that the spring reaction after that lasts much longer.
So it is bad for the seal and the spring.
I could hear the "tick" of air going through the barrière.
Regards, Robert
At least in break barrels, we can prove that. Again, see the accelerometer curve of the ASP-20 in the "Epilogue" and you will see that the second piston slam is HIGHER than the first one (the pellet driving one).
Pretty scary, . . . LOL!
Keep well and shoot straight!
HM
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But just wondering, I'm no expert but shouldn't these 150 gram-ish pistons and softer springs in these kits actually produce less recoil/shock that could harm scopes? The shot cycle seems indicate that there's less recoil going on. Guess we won't know for sure unless someone has an accelerometer and some spare time out there but yeah, shouldn't light piston = less recoil?
The recoil and surge is less, the physical speed of the piston is a little faster, this can translate into sharper movement even though its less overall travel. I have found the speed is more pronounced in shot feel in light weight guns, so my light weight HW50S experiments showed a harshness that you could feel, the weight of a TX and 54 etc looks to soak up the movement well and less is transmitted into the scopes, hence you can watch pellets fly easier, attach scope cams and they work like they do on PCP's etc.
Regard how much faster the pistons fly, i know my guns here (Tx rifles and 77's) have a locktime around 9 to 10ms, a HC can have 8 to 8.5ms which is like a pcp in speed but this is down to shorter barrel. Normal 77's weigh in around 12ms, the older 25mm guns 10 to 11ms so not much slower than my 22mm TX. I have never seen a 54 stock measured at 12fpe BUT i would imagine its around 12ms total locktime which puts piston flight time very close to 22mm. There is a lot of energy going into a stock 54 piston, big heavy brick that needs a good shove to get going.
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Since the idea of high speed photography is being discussed, has anyone considered running experiments with a compression tube made out of plexiglass? It would allow filming of the piston in action rather than guesstimating it’s dynamics from recoil measurements.
I’m definitely not a material scientist, but perhaps a plexiglass compression tube could be made on a mini-lathe and matched with a regular barrel/breech in a vise. Filming the piston and any associated flash from air combustion would be an amazing experiment. The first guy to do it first could be called (insert deep voice) - The man with the plexiglass gun! - Kind of catchy don’t you think? ;D
-Marty
Marty;
Sorry to have skipped your post.
The Cardews already did that and the problem was that the flash is so intense that there is little chance of seeing any detail.
If you look at this video:
https://www.youtube.com/watch?v=SkWJdWGdgaM (https://www.youtube.com/watch?v=SkWJdWGdgaM)
You will see that it would have to be a VERY expensive photographic setup to be able to see the difference in temperatures between the walls and the center of the compression chamber.
Thanks for reading!
HM
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I have an acrylic see-thru fire piston. Really cool device.
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Since the idea of high speed photography is being discussed, has anyone considered running experiments with a compression tube made out of plexiglass? It would allow filming of the piston in action rather than guesstimating it’s dynamics from recoil measurements.
I’m definitely not a material scientist, but perhaps a plexiglass compression tube could be made on a mini-lathe and matched with a regular barrel/breech in a vise. Filming the piston and any associated flash from air combustion would be an amazing experiment. The first guy to do it first could be called (insert deep voice) - The man with the plexiglass gun! - Kind of catchy don’t you think? ;D
-Marty
Marty;
Sorry to have skipped your post.
The Cardews already did that and the problem was that the flash is so intense that there is little chance of seeing any detail.
If you look at this video:
You will see that it would have to be a VERY expensive photographic setup to be able to see the difference in temperatures between the walls and the center of the compression chamber.
Thanks for reading!
HM
No need to apologize, I knew you would get to it in good time! Indeed I was aware of the Cardew experiments, so I have no doubt that there is combustion/plasma being generated within the chamber. My reason for suggesting the transparent chamber was aimed more toward the idea that it would be easier to measure how much piston slap or bounce was occurring given variations in pellet weight, TP diameter, spring settings and piston mass - capturing the combustion would be just icing on the cake. That said, if the equipment to perform the observation is out of reach of a hobbyist then scratch that idea :-X and move on to the next.
-Marty
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Marty;
Sorry for the long post:
It is often the case that we need to search alternative methods first.
Galileo didn't have a way to measure very short times when researching into free-falling objects. So, he used ramps to "slow" down the motion enough so that he could see.
Galileo was reasoning that if the theory held true for different degrees of inclination; from the very light inclination, very observable experiments; to the more inclined, and hardly noticeable by eye, ones; then the theory had to hold true for the vertical case.
Where the myth of deducting things from the leaning tower of Pisa came, I do not know, but we do know from his notes (impounded by the Inquisition and only fairly recently released for study by the Vatican), that the way he came to the conclusion was to study the fall of objects (spherical) down differently inclined ramps.
In this instance, Galileo was only following PREVIOUS researchers techniques and methods.
Because we do not have written records past the 7,000 BCE time, it is hard to decide to whom to ascribe the "invention" of what the French Enlightenment scientists decided to call the "Scientific Method" that is, essentially, what Steve did in all this process:
Changing ONE thing at a time.
For the hobbyist, sometimes this presents the problem that to change ONE thing (like TP diameter) it means either devising a "test bench" airgun, developing it from an established and well know platform, and then devising a way to be able to change that ONE thing.
To give you an example: this is what I did when designing the breech seal that is now standard in all my builds:
Used a platform that I knew well, and adapted one to look into the effect of different TP Diameters in the case of the different calibers and power levels. So, the steel insert that goes in the composite seal can have, basically, 4 different diameters, one for each caliber and one for the special 12 ft-lbs/ 0.177 " case.
How many experiments it took to arrive to these 4 numbers? about 50 different cases. Once "trends" can be established, then you start "bookending" the goal and you narrow down on both sides till you get the result you need. Which may not be the result you want, LOL!
Again, talking about this seemingly simple device, when the optimal diameter for energy transfer was found in one case, it conflicted with the need to make the piece perform the other duties assigned (pellet alignment and seating), and so the LENGTH was changed just enough for that particular caliber. It was somewhat of a challenge to change the length of the TP without changing the seating depth. But it was necessary to achieve an OVERALL OPTIMUM, which may not be the optimum for one purpose, but by compromising in one aspect, a better result overall could be achieved in ALL aspects.
The OTHER problem for hobbyists is that once they get good results, if someone asks them to create a duplicate part for THEIR needs, the answer you often get is "Sorry it's expensive for what it is".
Most people do not realize, or do not want to accept, that the person making things is not charging for the 5 grams of steel and the 2 grams of plastic that go into the piece, the value of the part is in the KNOWLEDGE that took to make it work the way it does, and the cost of all the tests and tries that were needed.
On the industrial side the problem is different: Boards (of directors) do not like to see what their bean-counters think of as a "too large an R&D budget". Specially in technologies that they consider "mature" and at the "end of the development".
All corporate boards are happier with "cash cows".
And it is difficult for a non-airgunner to understand the extremely fine nuances of what a "finely tuned", as opposed to a "highly strung", airgun is. Needless to say that absolutely none of the CEO's, CTO's, and COO's of airgun-making companies is truly an airgunner.
But within all this bleak picture, the users are taking the lead. And that is another aspect that is truly worthwhile about airgunning.
There is a very generous offer from one of the friends here to help defray some costs that would be associated with the research into the location (and therefore length and shape) of the TP in breakbarrels. I greatly appreciate that offer, now I need to find someone like Steve willing to do a number of experiments, and carefully document the results in the case of breakbarrels.
Hopefully we will find our person soon enough, but it is also an ongoing process that takes time.
To close this: Do not be afraid to experiment. It is always wise to ask if someone has done the experiment before and what were the results, but by all means, dream of something and go for it.
;-)
Keep well and shoot straight!
HM
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Hector,
That is so true. I got into airgunning specifically to experiment. I wanted to learn what these new adult airguns were capable of, how they operated and all that. Target shooting and hunting came later. Hunting was much later and rarely at all actually.