The SAGA of a DIANA 56 T/H

[fwbsport]

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.

[HectorMedina]

Second part in our four part study and exploration:

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

[Yogi]

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.

Hard to shoot straight in an earthquake,

-Y

[MartyMcFly]

Second part in our four part study and exploration:

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

[HectorMedina]

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.

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

[Beeman22]

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!

[HectorMedina]

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

[truck driver]

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?

[HectorMedina]

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

[HectorMedina]

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

Hope you enjoy!





HM

[fwbsport]

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?

[Buldawg76]

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

[MartyMcFly]

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

[dan_house]

been great stuff so far!!!
off to read part 3

[Nitrocrushr]

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

[Yogi]

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

[MartyMcFly]

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

[HectorMedina]

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

[MartyMcFly]

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

[HectorMedina]

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