GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: 3crows on August 13, 2022, 05:48:40 PM
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I felt I should just start a thread and not derail another. I have an aluminum air cylinder for my Marauder .25. I have the OE valve and hammer, the Tim Hill valve and light weight aluminum hammer and I have a JSAR Delrin MDS hammer. The MDS hammer is recessed and I assume intended to use the OE striker.
The TH valve and hammer were advertised as a match set so I sort of want to use his set up but with the aluminum air tube should I go with the JSAR MDS hammer with the Delrin out sleeve?
The TH hammer (with Peet striker) is very light compared to the OE and the MDS hammer kind of splits the difference. He provided a dry lube with it and of course I have spray on dry lubes as well.
So, yea or nea, on using the aluminum TH hammer with the aluminum air tube so I can use the TH valve? Or, MDS hammer with the OE valve or???????
Thanks for thoughts. (This is for a primarily hunting rifle so power takes precedence over shot counts but I do not want to go crazy, 45 fpe give or take).
James
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The JSAR Aluminum air tubes MUST BE used with a synthetic surfaced hammer ( Nylon, Delrin etc ... )
Factory steel hammer will gall tube in time as will a Hill Anodized aluminum hammer. They will work no doubt, but the air tubes internal surface where hammer slides will not !!
These AKA: MDS hammer come in a wide weight range pending application, regulated or not.
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Even synthetics can damage an aluminum air tube (or steel for that matter) if there is any grit introduced.... It will embed in the softer material and scratch up the harder one....
Bob
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TH Hammer (Peet striker) = 22.5 g
OE Hammer and striker = 74.2 g
JSAR MDS Hammer (w/OE striker) = 49.2 g ( https://www.jsairrifles.com/2022-MarauderArmada-Super-Hammer_p_23.html (https://www.jsairrifles.com/2022-MarauderArmada-Super-Hammer_p_23.html))
Do you think I can set up the MDS hammer I have to work with the TH valve? I have the OE hammer spring and I have the TH supplied hammer spring that came with his "Improved" performance kit (valve, hammer, spring, transfer port etc)?
I guess I am trying to ferret out a direction to proceed in?
I would not have thought a dry lubed aluminum hammer would be such a no go with an aluminum tube, both anodized? BTW, the MDS hammer results in the striker being recessed. I fabbed a spacer to set it out even with the face. Was thinking to use a #211 O-ring(s) as a buffer if set even with my spacer.
BTW, this is not a regulated rifle, I have a regulator and other items for my Gen 1 .25 but that project is well behind this one and mowing my yard ;).
James
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Heavier JSAR hammer and play with differing weight springs ... IMO
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I think Tim's matched set is primarily set-up for regulator use. With a light hammer, it probably has a light valve spring. I'd use the JSAR hammer, but might also change the valve spring.
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My guess is the TH hammer was designed for an OE steel tube and not for an aftermarket aluminum tube. I use MDS hammers in my aluminum tubes. I don't use strikers at all. Those just shorten the stroke length and can cause heavier cocking effort when trying for higher tunes. It is better to just have a flush hammer for max stroke length for less hammer spring needs and cocking effort.
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Running similar soft metals against each other tends to have them cold weld and gall. This is particularly bad for unclad aluminum and soft stainless steel alloys, that work harden significantly.
My suggestion is to find a commercial shop to electroless nickel plate the inside of the aluminum tube, just beyond where the hammer slides, but not into where the air pressure acts. The right EL process can yield a surface hardness of 70 RC. Very good for abrasion resistance. Such plating can be had with Teflon impregnation to act as permanent dry lube.
Then you can run an aluminum hammer that is anodized or even raw, without scratching the tube bore. You could ask plating experts if running two such nickel plated surfaces against each other would be a problem. Galling is not generally a problem with very hard materials (smooth, not rough or sharp), although with hardened steel, it helps to make the two slide parts have a different harness of at least 10 points RC.
It is not the hardness of a steel hammer that would chew an aluminum sliding surface. It is roughness, or sharpness in the hard part. A knife at 60 RC can't cut your skin, if there is no edge ground into the blade.
As Bob said, dust (oxides of silica, if it comes from the ground) is hard and its small contact area can easily cause the grit to act as lapping compound. Using a soft or plastic clad hammer won't prevent damage to the bare aluminum tube; if it imbeds such dust. Hard anodizing should help a lot, but better to keep sand based dust out. Hard to do in the field, with wind blowing.
To gain perspective, mild steel Marauder tubes with hardened hammers work OK in the field. If airborne silica grit gets into a stock Marauder at the hammer tube/interface, the hammer and tube just polish each other until the finish smooths out, and the fit loosens up a bit. Then, the clearance created allows the dust to migrate out, rather than wearing a trench all the way to Australia.
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I have used this place for "electroless nickel" plating of critical machine parts at work. Very gun friendly....
http://frankeplatingworks.com/plating-services/ (http://frankeplatingworks.com/plating-services/)
https://advancedplatingtech.com/electroless-nickel/ (https://advancedplatingtech.com/electroless-nickel/)
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Thanks guys, some good thoughts to consider.
Surely, like, well, I am not the only aluminum tubed Marauder out there? Wondering what valves and hammers and springs others have used?
I have nothing against the OE valve. It is making 44 fpe as it came from the factory but of courser the JAR hammer is lighter than OE so I will have to adjust something somewhere, lol, to stay even.
James
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Have a gen 1 M-rod with an extended Aluminum tube. have used OEM valves, WAR valves, JSAR balanced valves within it. Been used as a .177 , .22 & .25 cal with various breeches fitted.
Nearly all my m-rod R&D has been done on the platform and much of the last 5 years with the alloy air tube.
Just be noted .. The alloy tube is a "FOR LESS WEIGHT" issue only & outside that offers no advantage IMO over the factory steel air tube.
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Have a gen 1 M-rod with an extended Aluminum tube. have used OEM valves, WAR valves, JSAR balanced valves within it. Been used as a .177 , .22 & .25 cal with various breeches fitted.
Nearly all my m-rod R&D has been done on the platform and much of the last 5 years with the alloy air tube.
Just be noted .. The alloy tube is a "FOR LESS WEIGHT" issue only & outside that offers no advantage IMO over the factory steel air tube.
Yes sir, the weight is the issue, this is a hunting rifle for carrying (what is called still hunting) through the woods. Thus light weight and reduced size are my goals. My mountain rifle is under six pounds fully outfitted, loaded and with scope. I guess this will be a mountain air rifle or something, not sure at this point. Weight is everything.
You have done a lot, what hammers did you use or find most successful?
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You have done a lot, what hammers did you use or find most successful?
As the architect and original R&D person behind the entire Light Weight hammer trend with M-rods here now @ 10 years ago, I use my own MDS nylon hammers.
The core of hammer that creates the bulk of the weight has been 100% nylon, to aluminum, steel & brass pending desired weight wanted.
Years ago I once made and sold them for self install ( Did 100's ) Then as my tuning buisness got better I quit making them. With questions from others about taking up where I left off, had no issue and some others started making and selling them. Such is the history and can be researched with Motorhead member search & keywork of LW or Marauder or M-rod "Light Weight Hammer" All the original posts / R&D data should be in archives.
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I have run into a few issues. And please do not take these as complaints against any entity, just part and parcel to modifying motorcycles, guns, airplanes, whatever. It comes with the territory.
1. The JSAR MDS hammer must be useable only with their TSS. I will need to investigate that system/product because their hammer is not bored as deeply (due to counter bore for striker) and my available springs coil bind preventing cocking.
2. I have two different breeches, lever type, available to me and both have a barrel axis that is higher than the OE bolt breech. One is JSAR and the other is from some place in the ex-Soviet world. Both are beautiful. This means the barrel band will not install :o.
Note: I have discovered that levers look cool but are no easier to cock than the bolts so aside from looking cool I am becoming less enthralled with them by the minute.
3. PCP air rifles are a PITA. ;)
4. Are we saying that there is a member or person who can custom make a MDS hammer?
5. PCP air rifles are a PITA. ;)
James
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There are different types of MDS hammers. I use the flush faced ones with vent holes for best ES and maximum stroke length. Attached is one with a brass insert and weighs 55 grams and is a great all-around weight for most applications. Also, if you can, you want to eliminate the OE spring adjuster for more spring space. The TSS is great in this area as it provides maximum spring space for the easiest cocking effort and adjustment of spring(s) for a gap.
I would PM Rocker1 to make you one like these. All of mine were made by Rocker1 and were sold through JSAR at the time I do believe.
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PCP rifles are an opportunity:
to test your research skills
to test your creativity
to test your build skills
to test your patience
to exercise your ingenuity
to learn new things
to triumph over evil
to boldly go where no man has gone before
You don't need to be a trail blazer like Scott (Motorhead), but you can follow along like many of us airgunners.
Hunter
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In my 10+ years of EXTENSIVE R&D on PCP air rifles, Making parts to try .. mix & match testing finding combinations that suited specific caliber or power requirements yielded a perspective that then as in now STOPPED me from providing custom self install parts ???
That being few follow directions !!
Most read all the Chit Chat of others findings or stated "Hot Part or Pieces"
Then ... Proceed to make a self contrived combo of all best sounding parts and pieces into a custom build expecting the greatest air rifle ever put together !!
Seldom is this the case and Much $$ and Time gets wasted and a sour taste that PCP's are a pain in the butt develops :o If you fiddle without required knowledge YES that is a very real reality.
Now I'm not wanting to appear atop my soapbox preaching to the masses here ... It is a strong case for learning "Whats others before you" had learned by reading and UNDERSTANDING many of the finer points of the Why For the modern PCP operates beyond a simplistic basic understanding of how pneumatic weapons work, along with variants of how else it can be done. Not All Combinations work !!!
Face palm ... I'm done & hope no one has taken offense.
Scott S
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In my 10+ years of EXTENSIVE R&D on PCP air rifles, Making parts to try .. mix & match testing finding combinations that suited specific caliber or power requirements yielded a perspective that then as in now STOPPED me from providing custom self install parts ???
That being few follow directions !!
Most read all the Chit Chat of others findings or stated "Hot Part or Pieces"
Then ... Proceed to make a self contrived combo of all best sounding parts and pieces into a custom build expecting the greatest air rifle ever put together !!
Seldom is this the case and Much $$ and Time gets wasted and a sour taste that PCP's are a pain in the butt develops :o If you fiddle without required knowledge YES that is a very real reality.
Now I'm not wanting to appear atop my soapbox preaching to the masses here ... It is a strong case for learning "Whats others before you" had learned by reading and UNDERSTANDING many of the finer points of the Why For the modern PCP operates beyond a simplistic basic understanding of how pneumatic weapons work, along with variants of how else it can be done. Not All Combinations work !!!
Face palm ... I'm done & hope no one has taken offense.
Scott S
As an engineer and A&P and long time gun person and mechanic, I actually do read the instructions and follow them except where there are none and when it comes to this endeavor, there really are not. I see a lot of experimentation rarely with solid conclusion such as use this valve with this spring length and weight and this hammer and this --------- with part numbers or sources. And lacking that except for partial discussions, there is nothing to do but blaze one's own path.
As to the rifle. It seems to be shooting fine. Power is around 44 to 46 fpe with JSB Jumbos and I am getting good accuracy and consistency for a mag and a half. Right now I have depleted all of my scuba tanks to less than 2500 psi and my scuba compressor is down for repairs (more often than not). So I cannot do a full test run yet.
I think I need now these things:
1. A barrel band or confidence I can do without.
2. Important****** a hammer that is similar in weight and design to the Tim Hill hammer but with a Delrin/nylon outer sleeve.
3. A hammer similar to the OE hammer but again with Delrin or nylon outer sleeve for use with the OE valve.
I have also acquired a pile of other parts for other projects yet to be.
I did not install a mix-match of parts. I bought this and installed it:
https://hillairgun.com/product/high-performance-matched-parts-kit/
Months ago I started a thread when I began this journey to learn what others had done and I did get some useful info and links and I put that to heart. But for the most part I got:
1. A mix-match of suggestions with no end result.
2. Marauders are no good and boring and I should get this or that instead (which I clearly ignored ;) ).
No insult or meanness intended to anyone. This hobby and sport are for fun and the science of it all is part of the fun even when sometimes it becomes a PITA.
:)
And BTW, I bought from JSAR one aluminum air tube and I have two more in my shop I am making but those projects got shelved (and maybe JSAR will get around to making some more and I will gladly purchase another when they do :) ).
An interesting thing, I had to slightly shrink fit the barrel into the breach assembly, not that might be a PITA getting back out!
I will get in touch with the gent who makes hammers and see if he can help, Plan A, if that does not work I will come up with Plan B and C ----- .
Thanks all, really, I do appreciate one and all.
James
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James, here is a hammer idea a machinist friend of mine made and shared with me. It adds a little more weight without the galling with its threaded adjustable Delrin inserts. The cutout is for passing over the trigger sear. it would be a lot to take on but is good for ideas as it appears you have some skills. This hammer worked well for me to stop the galling and made cocking easier. I used six Delrin threaded inserts, so two on top to prevent tilt when cocking and four on the bottom for easy sliding. This is shown with my own OEM like adjustable DIY SSG I came up with at the time.
(https://i.ibb.co/XFZqfvr/F-I-F-H-01.jpg)
(https://i.ibb.co/ykKfkLb/20161030-133551.jpg)
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I remember that one ... exquisite work.
man .. back in the day we had so much M-rod innovation going on.
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I remember that one ... exquisite work.
man .. back in the day we had so much M-rod innovation going on.
Marauder mods were certainly on fire back then and you were a big part of it all along with Travis and many others. I do thank you for all your efforts and input to make these guns better performers. I couldn't tell you how many times I took my two Marauders apart for the latest mods and ideas coming out. It was a lot of fun trying them all out. It was also the reason for the free spreadsheet I created and shared so I/we could keep up with all of the different mod results.
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Yea, the good ole days! :D
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@triggertreat, very nice, brilliant. I am not up to that speed for sure!
My rifle as it sits today, with scope and bipod, 7.7 pounds, still no lightweight but it is lighter and balances much, much better:
(https://i.postimg.cc/gjFfCWLK/IMG-4130.jpg) (https://postimg.cc/YGRnFT34)
Many years ago I got into rebuilding and fixing up VW bugs and busses. It was said and it seems to have some truth to it, rebuild four bugs and you will have enough left over parts to build a fifth bug :). Well, applied to air rifles, soon, I will have enough parts to build another M-Rod. If I take this one back apart again, I might be there ;).
I am thinking to go back in and try the OE spring with one or two #211 O-rings to buffer the hammer. Of course, like I was saying before, the stumbling block now is a suitable hammer compatible with aluminum. I have the TH hammer slathered in graphite lube and the interior of the tube as well and it seems fine, no galling or damage. But of course, yes, this needs to be addressed in a permanent way.
James
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So went back into surgery this morning. Installed the MDS Delrin JSAR hammer. Used the OE striker and made an adjustment collar so I could set and lock striker position. Lubed with dry graphite. Set striker flush and used the TH spring which is short enough to cock without coil bind. The OE spring coil binds as it is a little longer length. No #211 O-ring for buffering since the JSAR hammer has a tiny bit of Delrin proud of the striker face as currently set.
Velocity now with the hammer adjustment all the way out is right at 860 fps with JSB 25.39 grain pellets. I think I will try to make or maybe, heck, just purchase the TSS system from JSAR so I can get a little bit of hammer free flight. Right now, all the way out the hammer is just kissing the valve stem with a bit of preload. I would like to be able to adjust a little and maybe tune it down to about 800 to 840 fps.
Of course, like I said, my highest test pressure has been 2300 psi and my compressor is down so it will be a few days before I can get my tanks refilled at the local dive store. He usually tops my tanks for free but a few are near empty since I just returned from a month long diving trip.
Accuracy is looking good but since I keep having to pull the scope each surgery I have not gotten to really dial it in for a complete test.
Rifle as equipped was 9.7 pounds, now 7.7 pounds for a reduction of a full two pounds. And that weight loss is very noticeable because it mostly came from forward of the trigger group. I think I need one of the (take off maybe?) plastic stocks and knock some more weight off. Anyone have one in good shape for sale?
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If with the SPRING currently used, and if poppet stem has HST bearing against it ( Preloaded ) Going to a TSS or SSG ( Free flight hammer ) WILL REQUIRE A STIFFER SPRING and will increase cocking effort.
Just FYI ...
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Many years ago I got into rebuilding and fixing up VW bugs and busses. It was said and it seems to have some truth to it, rebuild four bugs and you will have enough left over parts to build a fifth bug :). Well, applied to air rifles, soon, I will have enough parts to build another M-Rod. If I take this one back apart again, I might be there ;).
That is precisely what prompted me to build my bottle fed Marauder. I had pretty much everything needed to make another gun from spare parts except for the breech and much of the trigger group. Once I ended up with a spare bottle on hand (from switching the factory aluminum bottle on an Air Ranger to CF for the weight savings), I just had to do it - so I sourced the drop block and a few other parts and I was off an running. Glad I did it too - it is the most accurate gun I have now, running an LW Poly barrel. I don't shoot it often as it is a beast weight-wise, but it stacks pellets . . .
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The MDS hammer is self lubricating, so no need to add other lube. I have had some swell under high humid conditions, causing sticking conditions and need to be reduced in OD. You can also cause some to distort by tightening the hammer pin too much.
I'm surprised that the JSAR hammer has allot shallower spring pocket. The next time you have it out, could you post a depth measurement?
Before purchasing more parts, better to get "aired up" such that you can test the typical middle of the curve which is generally 2500-2600psi on 25 non-regged Mrod.
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If with the SPRING currently used, and if poppet stem has HST bearing against it ( Preloaded ) Going to a TSS or SSG ( Free flight hammer ) WILL REQUIRE A STIFFER SPRING and will increase cocking effort.
Just FYI ...
Good point, thanks. I would anticipate that being the case. Right now the hammer striker is barely preloaded. But the hammer adjustment is all the way out. I could recess the striker or cut a coil from the current spring. But I hate to do that at least until I get a few springs to play with. The JSAR breach has a good amount of leverage but I would not want the cocking force much higher than now. Mulling things over and it does get confusing since there are a myriad of directions I could go in. I think I am liking the JSAR MDS hammer and it is suitable for use with aluminum air tubes.
Thanks,
James
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The MDS hammer is self lubricating, so no need to add other lube. I have had some swell under high humid conditions, causing sticking conditions and need to be reduced in OD. You can also cause some to distort by tightening the hammer pin too much.
I'm surprised that the JSAR hammer has allot shallower spring pocket. The next time you have it out, could you post a depth measurement?
Before purchasing more parts, better to get "aired up" such that you can test the typical middle of the curve which is generally 2500-2600psi on 25 non-regged Mrod.
Yes good points and next time out I will get a depth for the spring recess. You can see it evident in the JSAR photos. Unlike the OE hammer (and TH hammer) the front side is recessed which allows the striker to be set much further rearward for what purpose I can only guess. I set my striker now ever so slightly recessed. Because the front side is recessed, this means the spring pocket on the aft side must be much shallower. Just eyeballing from my memory it is about .25 inches more shallow.
Yes, I need to get aired up because right now, I am down to 2100 psi on my cylinders and that is not enough really to do real testing. Yes, M-Rods seem to run in that 2800 to 2400 sweet spot. And I have not been higher than 2300 psi thus far. If I keep doing this and my scuba compressor keeps going TU I will just have to beg my wife for permission to buy a PCP compressor.
James
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I took a look at the current JSAR Super Hammer pics. It looks more like the Buffer Hammer, they use to make. I can see that the pocket is shallower. Keep in mind that with this shallow pocket, the 2.5" springs used with a TSS might not be able to be gapped, without the adjuster sticking well out the back. The TSS adjuster is larger diameter than the oem, at around 5/8". Probably your stock will need some minor work to allow for that. JFYI.
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I took a look at the current JSAR Super Hammer pics. It looks more like the Buffer Hammer, they use to make. I can see that the pocket is shallower. Keep in mind that with this shallow pocket, the 2.5" springs used with a TSS might not be able to be gapped, without the adjuster sticking well out the back. The TSS adjuster is larger diameter than the oem, at around 5/8". Probably your stock will need some minor work to allow for that. JFYI.
Keep in mind that the hammer slides further forward, hitting the valve face before the poppit bottoms out. Thus "the buffer hammer".
Hunter
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I took a look at the current JSAR Super Hammer pics. It looks more like the Buffer Hammer, they use to make. I can see that the pocket is shallower. Keep in mind that with this shallow pocket, the 2.5" springs used with a TSS might not be able to be gapped, without the adjuster sticking well out the back. The TSS adjuster is larger diameter than the oem, at around 5/8". Probably your stock will need some minor work to allow for that. JFYI.
Keep in mind that the hammer slides further forward, hitting the valve face before the poppit bottoms out. Thus "the buffer hammer".
Hunter
What problem is the buffer type addressing, what is the advantage offered?
I cut an aluminum spacer and threaded it to use as a locking nut. Using the OE striker I thread the spacer fully up and then thread the assembly into the hammer body. I then adjusted the assembly to have the strike where I wanted and set the locking collar and tighten it all down. I can lock the striker anywhere from proud to fully recessed. I set mine slightly recessed, about 1/64 inch. But, it cannot be adjusted with out disassembly. However, without the locking collar, there was nothing to prevent it self adjusting.
James
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The buffer hammer was designed to be used like a BStaley O-ring buffer. You are able to recess the striker, and keep a longer stroke. With the O-ring buffer, you turn the striker out, which reduces stroke. With valve porting and springs, you can get some better shot curves. I use the method in Prod style builds but didn't find a significant improvement in Mrods.
I got a used Buffer hammer from a GTA member. It is different from that hammer shown on JSAR. I used it like a standard hammer, and don't recall having the shallow pocket. I don't remember which Mrod it is installed in, to have a look. ::)
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I thought the O-ring mod was to absorb the last bit of hammer energy to prevent bouncing. Thus, whatever length the striker protrudes from the face of the hammer, the O-ring)s) would need to be ever so slightly greater otherwise the striker would just drive the poppet in all the way and the striker would then strike the rear face of the hammer and bounce back.
So, therefore I slightly recessed my hammer striker so that it cannot slam into the rear face of the valve body as the shoulder of the hammer will of course run into the valve body but being Delrin, I guess, might (?) reduce bounce back?
When it cools off I am going to go back to my aluminum air tube project. I started making one for my really nice GTA acquired Gen 1 .25. I will use the stock valve and try not to go off the deep end with it. I will have to change out the hammer of course. And I have a regulator set. It may get all of that and be tuned for more shots and accuracy at the expense of power. The rifle I am working on now is a hunter and I am still trying to get it to 50 fpe range plus or minus a bit.
What would be a source of material (plastic tubing) to cut custom length transfer ports from? Since my JSAR breech sits higher than the OE breech it therefore needs a longer than OE transfer port. I am getting some loss there.
James
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Buffering limits poppet lift. Finding the sweet spot of striker height at your ideal pressure is key. Now as pressure falls lower and poppet becomes easier to open the lift is being damped preventing excessive over dwelling.
IMO works best in Regulated applications. And ESPECIALLY Balanced valves where it was First made to address the over lift / dwell issues :o
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high pressure fuel tubing .
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Machined soda straw tubes with VERY square ends and assembled with a slight compressed length when breech tightens down.
Nylon works very well being it does have greater compressablity than acetal/delrin.
Tube NEEDS TO BE a very close fit to transfer hole threw the receiver block or it will balloon during the shot and create further leaks. * As well when tube is slightly crushed in place if too small to receiver hole it will just crush one side wall & fold.
Trust me ... been there & done this A LOT !!!
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I did get (some) 3000 psi air today. It seems I get to a certain point and beyond that the rifle just blows air for no purpose. This was with the JSB 25.39 grain pellets getting to about 860 fps. So I tried some JSB Heavy 33.95 grain pellets. Those seem to load the gun more and make better use of the air volume. Energy jumped up quite a bit.
These things are a science!
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Just to update. I now have the JSAR hammer with the OE striker 1/64 below surface. I have the TH spring and TH valve. I made my own transfer port. I set the hammer spring 4 turns in for my last run. One magazine goes from 2800 psi to 2000 psi and velocity goes from 810, 817, 820, 829, 817, 810, 805, 801. This is with JSB 33.95 pellets. Energy is then between 48 and 52 fpe. Accuracy is looking very good. Better with the 33.95 gr than with the lighter JSBs. This might be okay for a hunter.
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What does your buffer hammer weigh? I ask because the one I received didn't have a brass insert and wasn't heavy enough to make any hunting power with. I am not sure what your HS rating is either. I am just wondering if you have enough overall hammer energy to make good power is all.
To save ammo while tuning you can just fill to around 1600psi to 1650psi to set/test your peak velocity at mid pressure. Just refill back to that range after a few shots to stay in that range while tuning for the peak. This is the pressure range where you'll see the velocity peak. From there you can fill to 2900/3000psi to find the starting velocity and can then see what the extreme spread (ES) will be for a full string without having to shoot a full string and waste ammo while you're tuning. Just subtracting the peak from the starting velocity will give you the ES. This assuming you'll stop shooting the string once the velocity drops back down to the starting velocity.
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What does your buffer hammer weigh? I ask because the one I received didn't have a brass insert and wasn't heavy enough to make any hunting power with. I am not sure what your HS rating is either. I am just wondering if you have enough overall hammer energy to make good power is all.
The JSAR Super hammer I am using is the third below, 49.2 g:
TH Hammer (Peet striker) = 22.5 g
OE Hammer and striker = 74.2 g
JSAR MDS Hammer (w/OE striker) = 49.2 g ( https://www.jsairrifles.com/2022-MarauderArmada-Super-Hammer_p_23.html (https://www.jsairrifles.com/2022-MarauderArmada-Super-Hammer_p_23.html))
I wanted 50 fpe for at least one magazine and that is what I am getting now. The TH hammer came with the TH valve as a matched set and it is considerably lighter than the JSAR Super Hammer though both are lighter than the OE hammer. If the TH valve needed more weight why would he make a "matched" set with a light weight hammer? The only reason I am not using the light weight TH hammer that came with the TH valve is that I have an aluminum air tube and the advice is to use a plastic hammer with aluminum air tubes.
The set up on my rifle now, anything much below 1800 psi the velocity goes off a cliff. It seems to like the 3000 to 2000 range for the eight shot string I posted previously. I note also using the 34 grain JSB pellets the rifle makes a loud, sharp Ka-Pow for the entire shot string. Shooting the JSB 25 grain pellets, especially once below 2600 psi, the rifle makes a Bla---ahhaaat sound.
Good information, thank you,
James
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What does your buffer hammer weigh? I ask because the one I received didn't have a brass insert and wasn't heavy enough to make any hunting power with. I am not sure what your HS rating is either. I am just wondering if you have enough overall hammer energy to make good power is all.
The JSAR Super hammer I am using is the third below, 49.2 g:
TH Hammer (Peet striker) = 22.5 g
OE Hammer and striker = 74.2 g
JSAR MDS Hammer (w/OE striker) = 49.2 g ( https://www.jsairrifles.com/2022-MarauderArmada-Super-Hammer_p_23.html (https://www.jsairrifles.com/2022-MarauderArmada-Super-Hammer_p_23.html))
I wanted 50 fpe for at least one magazine and that is what I am getting now. The TH hammer came with the TH valve as a matched set and it is considerably lighter than the JSAR Super Hammer though both are lighter than the OE hammer. If the TH valve needed more weight why would he make a "matched" set with a light weight hammer? The only reason I am not using the light weight TH hammer that came with the TH valve is that I have an aluminum air tube and the advice is to use a plastic hammer with aluminum air tubes.
The set up on my rifle now, anything much below 1800 psi the velocity goes off a cliff. It seems to like the 3000 to 2000 range for the eight-shot string I posted previously. I note also using the 34 grain JSB pellets the rifle makes a loud, sharp Ka-Pow for the entire shot string. Shooting the JSB 25 grain pellets, especially once below 2600 psi, the rifle makes a Bla---ahhaaat sound.
Good information, thank you,
James
It could be that there is a light valve spring being used if the tune is dropping with each shot. This would also indicate too much hammer energy for the valve resistance. The TH kit I thought was for a regulated system which may be part of this, but I am not sure about his parts/designs. The noises also sound like this is what is going on. It all boils down to having the parts balanced against the pressure. You also should get at least two mags as well so sounds like a lot of wasted air from being too out of balance. Make sure also that the TP is not leaking. If you are careful, you can block the end of the shroud while cracking the valve open ever so slightly to see if it is leaking. You would need the Crosman degas tool to do this though. It's a trick I use. There should be back pressure at the muzzle end and no noises of air leaking with a properly sealed shroud.
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It could be that there is a light valve spring being used if the tune is dropping with each shot. This would also indicate too much hammer energy for the valve resistance. The TH kit I thought was for a regulated system which may be part of this, but I am not sure about his parts/designs. The noises also sound like this is what is going on. It all boils down to having the parts balanced against the pressure. You also should get at least two mags as well so sounds like a lot of wasted air from being too out of balance. Make sure also that the TP is not leaking. If you are careful, you can block the end of the shroud while cracking the valve open ever so slightly to see if it is leaking. You would need the Crosman degas tool to do this though. It's a trick I use. There should be back pressure at the muzzle end and no noises of air leaking with a properly sealed shroud.
Thanks, let me study on that information.
Tim Hill has three valve kits, the one I bought is not for a regulated rifle.
I have the degas tool, let me try that. I do not have indication of leakage but worth checking. The rifle is making close to 55 fpe, you really think I should get 16 shots at that power level?
This target shot five times at 25 yards with JSB 34 g pellets.
(https://i.postimg.cc/XNfVBJfV/IMG-4134.jpg) (https://postimg.cc/mhrx0Tpq)
J
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That's a great group but only at 25 yards. 50 yards and so forth is more telling of course.
As far as shot count two mags is certainly possible, but you have to eliminate any hammer bounce/wasted air to have a chance at that power level. The other thing is to tune the valve to be very efficient. A way to go about this in addition to balanced parts is to find your peak velocity without using more hammer energy than is needed and then backing off of that peak velocity with the hammer energy by 3% to 5% so you are tuned just below the knee of the peak or bell curve. This will ensure you are not overdriving the valve and also is making sure the valve is closed before the pellet exits the muzzle, so no air gets wasted. This also helps with accuracy, so the wasted air doesn't skew the pellet skirt on exit.
While you are checking for leaks, I would also pop in a new breech seal O-ring. You can get a bag of those and the other O-rings cheapest at the O-ring Store online. Just order the minimum quantities allowed. These are quality O-rings. Having a good breech O-ring is key to achieving a low ES and good shot count.
Attached are some of my .25 cal tunes with shot counts, FPE and ES using the MKIIs. Some are better than others while learning how to tune with different springs, hammers and valves. It just depends on what range you want to shoot as to what ES you can tolerate for shot count.
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That's a great group but only at 25 yards. 50 yards and so forth is more telling of course.
As far as shot count two mags is certainly possible, but you have to eliminate any hammer bounce/wasted air to have a chance at that power level. The other thing is to tune the valve to be very efficient. A way to go about this in addition to balanced parts is to find your peak velocity without using more hammer energy than is needed and then backing off of that peak velocity with the hammer energy by 3% to 5% so you are tuned just below the knee of the peak or bell curve. This will ensure you are not overdriving the valve and also is making sure the valve is closed before the pellet exits the muzzle, so no air gets wasted. This also helps with accuracy, so the wasted air doesn't skew the pellet skirt on exit.
While you are checking for leaks, I would also pop in a new breech seal O-ring. You can get a bag of those and the other O-rings cheapest at the O-ring Store online. Just order the minimum quantities allowed. These are quality O-rings. Having a good breech O-ring is key to achieving a low ES and good shot count.
Attached are some of my .25 cal tunes with shot counts, FPE and ES using the MKIIs. Some are better than others while learning how to tune with different springs, hammers and valves. It just depends on what range you want to shoot as to what ES you can tolerate for shot count.
Thank you for the chart and information. The chart is super useful to compare to.
My JSAR breach is brand new, I doubt it needs a new O-ring but good point to check it and get some new ones in hand. The O Ring Store loves me as I buy a lot of items for SCUBA gear from them :).
Right now I really do not have a peak velocity. I started at 0 turns in and was around 650 fps, 2 turns was 700 and 4 turns jumped to 820 and velocity just keeps going up until the hammer adjustment screw runs out of threads. But right around 850 fps with the 34 grain pellets the sound changed from Ka-Pow to the same Blaaaaaat sound I get with the 24 grain pellets. So I backed off from 4.5 turns to 4 turns and that is giving me an average of 820 fps for those eight shots.
I am sure improvements can be made even if I need a different style or weight of hammer or hammer spring but right now I am perched over an abyss of ignorance :( and mulling over my next direction of experimentation.
That target was using my plastic bipod on a wobbly garden table. My rifle bench was being occupied by some wasps that will soon find an eviction sign on their property.
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I think, between this thread and my other concurrent one that I may go in next time I take the rifle down and add two or three #112 O-rings in front of the valve. Then run my striker out so that it is forward of the end plane of my recessed Super Hammer and then lock it down there, as if it were resting on the face of the hammer (as was the OE tune on my OE hammer). Then run my hammer spring fully out and start over.
I think I am opening the valve, dwell time, too long. The front face of my striker is 1/64 recessed below the face of the hammer, hammer spring 4+ turns
I did try two #112 O rings (BStaley mod) originally but was using the TH aluminum light weight hammer and I was just not getting anything promising. At least now I have plenty of power and a lot of wasted air it seems.
James
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While I'm not sure how Tim is doing it with a conventional valve, it sounds like it was working with the light hammer. The heavier hammer is causing excessive bounce. While you might be able to tame it with the O-ring buffer, should also consider just getting a lighter hammer.