Snowpeak P35X fpe limitations

[JohnnyDK]

I recently purchased a P35X in .177, primarily because of the added 65 cc plenum and the longer barrel. I purchased it from mundilar in Portugal so no power limitations.


However, I can’t get it to shoot faster than 860 fps with JSB Exact Heavy 10.34 grains even with the hammer spring fully adjusted.


I’ve also tested:

• JSB Beast 16.20 gr = max 720 fps.
• JSB Monster 13.43 gr max 776 fps.
• JSB KnockOut Slugs in both 10.03 gr and 13.43 gr max fps = even less then the two pellets mentioned above.

• I expected it to have around 29 fpe with the jsb beast 16.20 according to others reviews, but I'm close to half of that fpe, 18, 65 fpe / 720 fps when shooting the jsb beast. 16.20.

Has anyone experienced similar performance limitations – and found a solution?

 

[JohnnyDK]

That's the regular P35. The P35x has a longer barrel and a 65 cc plenum.

I don't own that rifle but I was researching it a little while back and I came across these specs on Krale. According to this chart, you're getting the advertised power. 25 joules = 18.4 fpe. View attachment 573812

 

[Racing]

Not knowing the X version, while being very familiar with the 15 and 35 (as well as the M-16 which uses the same setup) something´s amiss here - as has been noted.
120 bar might be on the low side for any appreciable level of performance but should non the less suffice way beyond what you´re getting.

Sorry to say it to me sounds like the unit needs to come apart.
Sure. It CAN be something misaligned, i wouldn´t bet on it though.
However.
All is not lost as that family of guns are fairly simple to tear down. Only real caveat being the actual valve body, which is held in place via a simple pin that runs through the main receiver.
To get that pin out do NOT use force. Instead find a small wooden pin/dowel to put pressure rearwards on the actual valve housing where it sits (for instance by having said dowel in place as you lean into a table or similar) and then just push it out.
With it comes two o-rings, both are essential so make good use of silicone grease upon reinstall.

Albeit the unit is from Portugal it might still be that the exhaust port on the valve housing is restricted, which is the main reason for looking into exactly that. This is, general, how Snowpeak restricts their pcp´s for various markets.
If so just take a drill bit to and be done with it already.

That being said also check that the hammer is free to move upon release. That it doesn´t snag or gets held on anything down its bore.

If your unit carries one of the restricted valve bodies it´s quite evident right off...

....as exhaust port will be REAL small. Note the one, marred, o-ring btw.

 

[JimD]

If you haven't already tried increasing the hammer spring you should. You always want to know what the peak velocity you can get with any regulator setting so you can tune the gun. The P35X hammer spring in the one I have is not the same as the spring in my bullshark which is the same as my P35s. The P35X has a little bit shorter spring but it is made of thicker wire. 1.3mm instead of 1.2mm. So it is a more powerful spring. It is possible it is too powerful for a 120 regulator setting. Having too much hammer spring can reduce velocity. I do not understand why but I've seen it happen. So if you turn the hammer spring adjuster all the way out and the velocity never decreases or increases it would suggest the hammer spring is too stout for your regulator setting. I also think you could put your bullshark spring into your P35X. I have a P35X in my P35-25 right now. Works great. It's gotten hot here now and my P35-25 would not open the valve even though it had before in cooler weather. Putting in the P35X spring solved that and I was able to reduce spring force by over 2 turns of the adjuster without decreasing velocity. So I know it is a stouter spring.

I could just be that your spring is not adjusted enough to fully open the valve or it could be that the spring is too strong and is applying too much force. The only way to know is to get out the chronograph and do some shooting varying the hammer spring to see what happens. If you cannot reduce or increase velocity with the hammer spring I think that means the spring is too powerful for the regulator setting. Putting in the bullshark spring and getting a different result would confirm it.

I also have a P35X barrel on my P35-25 and it definitely increased the velocity. About 50 fps. I could not get the airtube with the added plenum to work on my P35 but the barrel length definitely helps.

You need data from hammer spring adjustment to determine better what is going on and what to do about it. If you can get that data I would be happy to offer more suggestions.

 

[JohnnyDK]

This came in the package.. Could it have something todo with the limited fpe?

Not knowing the X version, while being very familiar with the 15 and 35 (as well as the M-16 which uses the same setup) something´s amiss here - as has been noted.
120 bar might be on the low side for any appreciable level of performance but should non the less suffice way beyond what you´re getting.

Sorry to say it to me sounds like the unit needs to come apart.
Sure. It CAN be something misaligned, i wouldn´t bet on it though.
However.
All is not lost as that family of guns are fairly simple to tear down. Only real caveat being the actual valve body, which is held in place via a simple pin that runs through the main receiver.
To get that pin out do NOT use force. Instead find a small wooden pin/dowel to put pressure rearwards on the actual valve housing where it sits (for instance by having said dowel in place as you lean into a table or similar) and then just push it out.
With it comes two o-rings, both are essential so make good use of silicone grease upon reinstall.

Albeit the unit is from Portugal it might still be that the exhaust port on the valve housing is restricted, which is the main reason for looking into exactly that. This is, general, how Snowpeak restricts their pcp´s for various markets.
If so just take a drill bit to and be done with it already.

That being said also check that the hammer is free to move upon release. That it doesn´t snag or gets held on anything down its bore.

If your unit carries one of the restricted valve bodies it´s quite evident right off...

....as exhaust port will be REAL small. Note the one, marred, o-ring btw.

 

[JimD]

If there is a small, like1-2 mm hole on the small end and a bigger tapered hole on the big end it may be an alternate valve seat. You may have one with a small outlet in the gun to limit power.

 

[JohnnyDK]

The first ting I did was adjusting the hammerspring, with the chronograph to know the maximum velocity
The maximum Velocity I measured is the ones I wrote in the initial post and that was received by 2.5 turns to the right. Further turns reduce the velocity of the pellets , so your description is pretty spot on.

If you haven't already tried increasing the hammer spring you should. You always want to know what the peak velocity you can get with any regulator setting so you can tune the gun. The P35X hammer spring in the one I have is not the same as the spring in my bullshark which is the same as my P35s. The P35X has a little bit shorter spring but it is made of thicker wire. 1.3mm instead of 1.2mm. So it is a more powerful spring. It is possible it is too powerful for a 120 regulator setting. Having too much hammer spring can reduce velocity. I do not understand why but I've seen it happen. So if you turn the hammer spring adjuster all the way out and the velocity never decreases or increases it would suggest the hammer spring is too stout for your regulator setting. I also think you could put your bullshark spring into your P35X. I have a P35X in my P35-25 right now. Works great. It's gotten hot here now and my P35-25 would not open the valve even though it had before in cooler weather. Putting in the P35X spring solved that and I was able to reduce spring force by over 2 turns of the adjuster without decreasing velocity. So I know it is a stouter spring.

I could just be that your spring is not adjusted enough to fully open the valve or it could be that the spring is too strong and is applying too much force. The only way to know is to get out the chronograph and do some shooting varying the hammer spring to see what happens. If you cannot reduce or increase velocity with the hammer spring I think that means the spring is too powerful for the regulator setting. Putting in the bullshark spring and getting a different result would confirm it.

I also have a P35X barrel on my P35-25 and it definitely increased the velocity. About 50 fps. I could not get the airtube with the added plenum to work on my P35 but the barrel length definitely helps.

You need data from hammer spring adjustment to determine better what is going on and what to do about it. If you can get that data I would be happy to offer more suggestions.

 

[JimD]

Have you looked at the side of the action block for the pin that holds the valve body in the block? I forgot about that pin and the post by "Racing" caused me to go look at my P35X action block and sure enough, there is a pin through the action that secures the valve body to the block. I pushed it out with a drill bit that fit into the hole in the action block and was able to easily tap the valve body out of the block (with a larger twist drill slightly smaller than the small end of the valve body). I used a dead blow hammer made of plastic doing this which did not damage the twist drill. You should not need to apply much force. You want to put the small drill to push out the pin in the side that has a bit of a recess, not the side that is about flush. There is some ridges on that pin that will be on the flush end of the pin. You can then compare the valve body in the action block to the one in the bag. I suspect the outlet from the valve body is much smaller for the one in the gun than it is in the valve in the bag. Swaping that one piece may give you the power you should have.

I must have tapped that pin out of my P35-25 before I drilled out the passage from 75% of bore diameter to 85%. That will further increase velocity but you may or may not need that much. You have to be careful to remove all the metal chips the drilling creates and the barrel port needs to be opened up the same way for the maximum benefit.

You need to remove the air tube and poppet first and the hammer from the action block (drain the air first, of course). The hammer will come out pretty easily if you remove the trigger block from the action block (to get the sear out of the way) and move the cocking mechanism forward so it is not in the way (after backing out the hammer adjustment screw and removing the hammer spring). Quite a bit of disassembly but no worse than changing the regulator IMHO.

Simplest is just swap out the valve bodies and put it back together.

 

[Racing]

This came in the package.. Could it have something todo with the limited fpe? View attachment 574063

Here we go, cause that is the unrestricted valve body.
Replace it and replace it now.
There´s several tutorials on YT how to if you feel way in over your head.

 

[Racing]

Btw.
For a word of advice on the matter then.
Porting, as in opening the exhaust, transfer and barrel port up in dimension, is... more the norm than anything.
I ran this on an M-16 bottle version, which in essence is the exact same setup. This for a 25cal gun where i added a massive plenum, and as such wanted to run ports on caliber size.
However doing so i "broke into water".

Ie; as i came to port the transfer port out to 6.3mm what happend was that i drilled into the flange area for the valve body such that the o-ring that´s to seal vs the HPA part of the unit really ... didn´t anymore as the o-ring in case lacked support.
So.
Whatyado at a place like that?

Well. What i did was turn a rather thin steel shim to be put beneath said o-ring (the large black one in the pic) and as the story goes that brought the gun back to working as should.
What i´m saying is that when it comes to porting these guns thread gently and carry a BIG *ss gun!
To be blunt what really needs to be done is run an aluminium so called weld rod down the stock transfer port set with Loctite and then a new such port needs to be drilled slightly inclined.
As to why Snowpeak seems to have stuck with this solution... no idea.
But 65cc´s of added air speaks volumes in my book and the current placement of said hole no doubt puts a limit to what can be had.

Where said M-16 ended up?

Well, spite the rather limited barrel length that thing went beyond 130J (95fpe) easy.
So that it CAN be done is to be put beyond debate.

 

[JimD]

I drilled my P35-25 out to 85% of it's .25 bore or about .2125 inches and that did not create any issues, it just increased velocity. That is what I plan for the P35X I am trying to fix. It's entire passage is about .165, 75% of .22 inches. I think I am at the position of being able to do it now, I just need the time.

 

[JohnnyDK]

That the case so. It seems like that's the reason for the limited fpe.

If there is a small, like1-2 mm hole on the small end and a bigger tapered hole on the big end it may be an alternate valve seat. You may have one with a small outlet in the gun to limit power.

 

[JohnnyDK]

Awesome. Now I know why the limited fpe/velocity.. I'll look into some YouTube tutorials.
Really Appreciate the outstanding advice from all of you guys

Here we go, cause that is the unrestricted valve body.
Replace it and replace it now.
There´s several tutorials on YT how to if you feel way in over your head.

 

[Will74]

This came in the package.. Could it have something todo with the limited fpe? View attachment 574063

Now that's more like it!
I had no idea they made things so small.
I have enlarged pretty much everything on my P15.
Hopefully the air passage through the block is of decent size on your Snowpeak. Then there's the transfer port. Not much more in the way...