My new P35

It shouldn't be, but unfortunately it is. Snowpeak is famous among tuners for their disappearing trigger pins.
I was adjusting the first stage pull weight with the set screw and the spring along the connecting rod from the trigger to the sear unit and I noticed the pins just slowly dancing their way out of place. After I was done loosening some weight the pins wont even stay in place anymore. Luckily I caught them before they disappeared into Narnia. For now I just put some scotch tape on both sides of the hole but it looks like I'll have to order some extra pins just in case they decide to go out for some milk.
 
I was adjusting the first stage pull weight with the set screw and the spring along the connecting rod from the trigger to the sear unit and I noticed the pins just slowly dancing their way out of place. After I was done loosening some weight the pins wont even stay in place anymore. Luckily I caught them before they disappeared into Narnia. For now I just put some scotch tape on both sides of the hole but it looks like I'll have to order some extra pins just in case they decide to go out for some milk.
I lost one of mine when I had my Bandit apart. I used a cut off finishing nail in its place for a few months until I got lucky and found the pin.
 
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As you begin to exceed 40 fpe, which typically requires higher reg settings, this platform greatly benefits from reducing poppet OD/sealing margin diameter. If you inspect the poppet and valve seat you will see the poppet's sealing margin is much larger in OD when compared to the valve throat itself. This means the valve requires more hammer strike to open than is necessary.....

The OEM poppet head can be reduced in size enough to significantly reduce required hammer spring.

Ideally going to a peek poppet barely large enough to not wedge itself in the valve throat will reduce hammer strike to the absolute minimum required.

In .25, the valve throat area is very restrictive. Converting the poppet to a 2mm stem , or machining a waist in the OEM poppet stem down to 2mm or so will allow for 75-80% of bore area in the valve throat.

Combining the increase in valve throat with a decrease in poppet sealing margin OD will result in a gun that exceeds 50fpe, easily, and on less than 125 bar reg setting. Setup this way, one will find the OEM hammer spring to generate excessive preload, even at the lowest HST setting. Then you can clip a coil or 2 off the OEM spring to find the right amount of HST. No hammer weights nor hard to cock springs required.

Denovich has my old p15 which is setup this way, he can provide some feedback on ease of cocking and energy levels at relatively low reg settings. I documented the trial and error of this journey over on GTA.
 
A lathe would be ideal, but not a requirement. In my caveman shop I have only used my drill press and/or dremel, using files and sandpaper as cutting/finishing tools. High RPM's and a firm "tool" rest help with concentricity, using a light touch, as not to burn. For these crude methods my experience has been that peek is much more forgiving to work with, likely due to its resistance to heat. I use peek exclusively for my poppet material.

As long as you do not introduce debris into the system via dirty air or corrosion, my experience has been peek poppets last almost indefinitely. The 2mm stemmed peek poppet in the gun I mentioned that Denovich has, before I shipped the gun to him, the poppet had outlived many many tins of JSB's, I know more than 50 tins minimum, likely closer to 100 tins went through that valve and hammer system....

Over the years Jason/Nervoustrigger has written extensively on DIY poppet making techniques, I believe both here and over on GTA.
 
Thanks Mike. I reduced my regulator setting a tiny amount today and seem to have fixed my "first shot lower velocity" issue. With a max'd out hammer spring. I need to shoot this some and confirm I really did fix the first shot. Velocity increased about 10 fps. I might be happy with where the gun is but, if not, a small reduction in the poppet diameter seems worth a try. I do not have a lathe but do have a drill press and fine sandpaper. And a dremel but I do not envision using that. I looked at a bunch of your posts on GTA tonight. I will probably go through Jason's tomorrow. Thanks for generously sharing your knowledge.
 
Thanks Mike. I reduced my regulator setting a tiny amount today and seem to have fixed my "first shot lower velocity" issue. With a max'd out hammer spring. I need to shoot this some and confirm I really did fix the first shot. Velocity increased about 10 fps. I might be happy with where the gun is but, if not, a small reduction in the poppet diameter seems worth a try. I do not have a lathe but do have a drill press and fine sandpaper. And a dremel but I do not envision using that. I looked at a bunch of your posts on GTA tonight. I will probably go through Jason's tomorrow. Thanks for generously sharing your knowledge.
Jim, I've enjoyed following your journey with the platform. I wrote a lot about the p15 over a few years, but keep mind it was a LOT of trial and error.....so i would recommend giving the later posts more weight than early posts. Really I didn't begin to fully understand the platform (and PCP function in general) until I converted it from
22 to .25 using an Mrod barrel. The early .22 posts were mostly learning what NOT to do, lol.

I recommend careful study of the relationships between poppet travel, valve seat/carrier and hammer travel before making any changes. It is easiest to do this with these pieces removed from the gun.

This is a very tight space and tiny changes can affect other aspects of neighboring function/operation

For example...
Reducing poppet od will result in the poppet sitting deeper in the funnel-shaped valve seat. In turn this will cause more stem protrusion....in turn this reduces hammer travel, reducing hammer strike capability in an already marginal syste.

Measure stem protrusion, at minimum do not exceed the OEM measurement. Also recognize that any protrusion greater than half the throat ID may be considered as surplus, and candidate for reduction/shortening. This will actually increase hammer strike capability due to increasing hammer travel.

There is a very fine line here where you can significantly increase hammer strike by increasing hammer travel. Hammer travel can be maximized by both reducing stem protrusion as well as one can machine of a mm or so of the hammer face, shortening its length, increasing travel in the process. In this application the increase in travel far outweighs the slight reduction in hammer mass...too much stem protrusion= too short of hammer travel...too little stem protrusion and the hammer will bounce off the valve, reducing dwell and of course velocity. Optimization of this area can yield performance previously unattainable.

With this platform in particular, as one is working towards a goal of >45fpe with good efficiency at lower reg settings/higher shot count, step 1 should be to get the porting to 75- 80% of caliber. After that is achieved, fine adjustments around the valve and hammer system like I described above will make achieving the goal much easier. A 2mm stemmed, minimum diameter peek poppet will make exceeding 60fpe at 140bar or less a relatively easy task........45fpe will come at less than 130 bar, likely as low as 110-115bar.

It is a very capable platform, my learnings here made it relatively straight forward to achieve my desired goals when shifting over to the Gen 1 Taipan Veteran. Other than the differences in quality/precision/robustness, the Veteran has slightly more hammer strike capability than the p15, with a couple more mm of available hammer travel, a couple more grams of hammer mass, and a much more powerful hammer spring system. In comparison, my veteran Long is a >60fpe .22 slug shooter at 135bar, or a >85fpe .25 slug shooter at 145bar depending on which barrel I am using. The key change in the Veteran was increasing throat area to 85%or so of bore area by reducing stem diameter.....IMO this is the missing link for many who experienced hitting a "wall" in their journey towards higher energy slug shooting with their OG Veteran.

I hope you proceed in optimizing the valve and hammer system, this will make your .25 P35 really perform. Some of this may apply to the smaller calibers as well, but I have no relative experience to share. .177 and .22 slugs likely require a slightly different recipe.
 
I think I am done modifying my P35-25 except for probably a new wood stock. It has the first one I made of softwood and I can do better. But it works. The light in the picture is not great to reveal detail but the plenum extension is installed and with my in shroud moderator the shroud was still a little shorter than the air tube. But I put in my DonnyFL adapter for a moderator and that made it slightly longer. I did the same thing with a short hair curler and a couple baffles. I also included pictures of some 3/4 plywood scraps I shot at 25 yards. Nielsen 26.8 grain slugs, 31 grain Baracudas and JSB 33.95 grain all went through. Any should go through a skull of a fairly large animal. Accuracy is still so-so. I shot one 5 shot group at 30 yards that was about .15 center to center with the Nielsen slugs but I could not replicate it. Most were 1/2 inch or bigger. I had a very limited supply of pellets but MK1 JSBs seemed to shoot the best, probably better than the slugs. I ordered more to make sure. I'm still hoping Krale delivers the new barrel I bought from them in April. My phone sound app says the noise it makes is about 80 db at my shooting bench. Likely a little louder in front of the muzzle. Sounds quieter than the pellet hitting the trap, however.

My final fpe is a little over 43 fpe with slugs and about 48 fpe with heavy pellets. Not quite the 50 target I had but close enough, I think. I tested penetration of these projectiles and a few others today in wet paper. The Nielsens expanded but that cut their penetration to almost exactly the same as 14.66 grain FTTs out of my Prod. That's my minimum penetration standard. So they would work but would rarely exit a squirrel. Would make big holes but .25 holes drop them very quickly. The Heavy pellets went about 50% further. That is more what I want, I think. Enough penetration they should kill a racoon pretty well with a well placed shot. My hammer spring is almost max'd out with the brass shim that came with the plenum extension. I had to adjust the regulator to eliminate a first-shot-low issue with my first increased setting. I think it is now about 135bar. The hammer spring is just below the point that gives me maximum velocity. I lost less than 1 fpe turning it down and it cocks better and seems a bit more accurate. I may play with this a little more when my pellet order shows up. My prior tunes of this gun and my two other P35s results in increase velocity as the gun comes off the plenum. That does not happen with this tune on this gun. It just slowly decreases. I did not do a full shot string but did several strings of 20 shots or more while monitoring the pressure. From that I calculate I will get 43 shots from a full charge. The ES over 20 shots or so is consistently about 7 fps. Seems like a pretty good tune.

The poppet diameter change Mike recommends still seems interesting but I think I will mess with other things, at least for now. I'm pretty happy with my almost 50 fpe P35. Maybe it will get to 50 next summer but I doubt any target will be able to tell the difference. The 33.95 grain pellets are going just below 800 fps but I looked at the trajectory and I think it's flat enough. Their BC is almost as good as the Nielsen 36.8 slugs. Baracudas go faster and are almost exactly the same fpe but so far it looks like the JSBs are more accurate.

P35-25 with plenum.jpg


plywood front.jpg


plywood back.jpg
 
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I had a .22 Skyhawk that had most of the mods that Mackerel5 made to his (now my) P15. But the cocking action wasn’t as nice. He did a better job on that.

My .22’s barrel was so-so on arrival. The lede was especially bad. Pellets took some abuse getting shoved in. The crown looked like it had been machined with a dull beaver. It also had a few tight spots when I slugged it. I didn’t make all the changes at once, I just got a little more aggressive with each iteration until performance was good enough that I stopped playing with it. 2” group at 100yds with NSA 17gr slugs was the best I could do (at night with an NV scope… harnessing my insomnia)

Getting them quiet… still a work in progress. Subscriber made some designs for me. In shroud you don’t have a lot of volume/length to work with. His designs that had a section that extended beyond the end of the shroud worked best.

I wound up buying a 30/28mm OD/ID CF tube ($30 on Amazon for two 500mm long). I used it to make a longer shroud. Since the application was custom and I didn’t want to monopolize Subscribers pro bono design work I’ve been fusing bits of his design and my own. My P15 in .25 is shooting JSB Kings at 880fps The .25 pellet whizzing through the air and impact are now more obvious than the shot itself. It is now much more pleasant sounding than my .22 (which also saw lots of experimentation in this regard).

(Lots of amusing failures along the way in silencer development. Most good ideas aren’t easily realized. Stupid hair curler/fender washer style designs are surprisingly effective. And if you can live with longer, it’s easier to get quieter.)

I also machined a poppet on a drill press… my PP700 had some debris in the valve seat marring the surface of the poppet and preventing a good seal. I used a hand file for the shaping.

But it is the perfect first project on a lathe. You know you want one. Maybe Harbor Freight has their mini lathe on sale of BF. Treat yo self. :). Gunsmithing is a great source of project inspiration for a lathe and well suited to the limits of a mini-lathe. (I do have a lathe, but it was out of commission after I moved.)

End of ramble…
 
I will try to keep this update short. I had to order more pellets but have decided JSB MK II 33.95 shoot best for my retuned 25 caliber P35. I am getting 1/4 to 1/2 inch groups at 30 yards with an occasional flyer that is quite possibly me. I plan to try some FX 33.95 and they might shoot a little differently but my guess is they will be close. These groups are better than I could get at my previous ~32 fpe tune. I tried to get the pellet probe out of the gun today but quit without removing it. The back of it has a much larger diameter so to get it out what appears to be a pressed in bushing has to be removed from the action block. I did not want to risk damage doing that. But I had it loose so I drilled it out to the same 85% diameter I used for the transfer port, barrel port and the passage between them. I then polished it a bit with some diamond ball dremel tools. I seem to have gained 4-5 fps. Velocity is now between 800 and 805 with the MKIIs. A little less than I was hoping for but 820 fps (50 fpe) would not really be that different. I'm encouraged enough with the accuracy I will probably try a 30 yard challenge target or two with it. Before the retune it would only do ~155. I'm thinking 175-180 may be possible now. Not the 190+ of my other two P35s but better.
 
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billhill, I am not anxious to get rid of any of my extra stocks but might be persuaded to help out a fellow airgunner. All three of my P35s are wearing hardwood stocks now. I have a softwood stock that I am not using, and three plastic P35 stocks that I am not using. The plastic stocks are not in as received condition, however. I needed another inch length of pull so I put spacers on them which required removing the butt pad. It is reattached but taking it on and off has affected the fit slightly. The softwood stock is made to my 14.75 inch length of pull. The softwood stock weighs 1 lb 1 ounce on my fishing scale and I weighed one of the plastic stocks at 1 lb 3 ounces. I don't know what a bullshark stock weighs so I don't know if this is less or not. Bullsharks also have another 40mm of barrel which must also increase their weight a little.

Since my last post I've shot a 192 30 yard challenge target with my P35-25. Quite a bit different from the 155 I shot before the retune. That was with JSB 33.95 mkii pellets. The best of the couple targets I've shot with FX 34 grain is 187. I put 5 into the 8 ring of a 30 yard challenge target on Christmas eve, however (at 30 yards). About 5/16ths center to center. Just for grins I shot a target with my P35-177 and shot a 178. That gun has given me a 194. So I think if I practice a bit the P35-25 will do significantly better. Might even shoot a 200 like my P35-22 has. I ordered a barrel from Krale for the 25 caliber in April of this year. It is now on a ship and should get here in January or February of next year. So I have that to test too. The barrel I'm shooting has about an inch of rifling drilled out so I may gain more velocity from the replacement but the big thing will be to determine which is more accurate.
 
I really wanted a P35 or the Stoeger XM1 bullshark, but not at the $450-$500 price.
I will wait for a sale.
It’s really a lot of rifle for the price. Mine has performed great out of the box. From others experience doing a little work will even improve them more. I’ve also owned a flashpup in the past. The Snowpeak is a far better product.