Tuning FX Impact/Maverick/Crown brass regulator piston done right

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Hi. I immediately contacted Vetmx since I stay 100% behind my products. He is unable to go past 150bars on the bottle reg using a brass piston. The dimensions of the shank are the same as in the original piston (the measurements are taken by Vetmx):
dimorig.png

dimbrass.png


The only difference is in the wall thickness on which the pressure acts on:

dimorig2.png

dimbrass2.png


This wall is about 0.35mm thicker than the original one:

1668884301868.png

That was done on purpose to make the piston more robust since that is the wall which the pressure acts on. However, it does not influence the regulation range. In such case I would say the issue may be related to the washer stack.
 
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I never had a recharge time problem with the stock pistons. Your reg recharge time depends on quite a few things, not just the piston. Mainly your caliber and reg setting. Then the condition of your washers. My .25 and .22 have the exact same reg settings. My .25 recovers faster. Bigger gulp of air. As far as creep goes, right now my brass pistons are both creeping 4b in 12 hours and that’s where they hold. Where I have my hammer spring set the 4b creep does not appear to be a big deal. During a shooting session they are spot on. It’s too windy to shoot today so I will mess with the second reg to see if I can get it to stop creeping at all. I don’t concern myself with first reg creep.
 
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Although the surface quality of delrin seating of my pistons cannot be achieved in any mass production - one still needs to give it some time to break in. The sealing force which acts on the delrin disk is small and the surface quality needs to be as good as possible. Even the sharpest lathe knife cannot give the surface quality which is good enough (I verified it during my testing) hence some polishing with high quality abrasive paper is needed. What is more, when one uses a lathe knife the worst surface quality is in the middle (the most crucial area) due to the lowest cutting speed. My delrin disks are polished with 8000 high quality abrasive paper. That is just one side of the equation though. The second part is the quality of this surface:

IMG_20220805_132018~2.jpg

I polished this surface with 3M fabric recommended by Ernest and I recommend it as well. My reg creep is virtually non-existing - up to 1 bar. Vetmx, you should cut your creep by 1-2 bars by allowing for some break-in time.

As of the reg recovery I had one situation where my piston helped in that matter. Original delrin piston didn't have the channel big enough - there could be some debris in it as well. Once my piston was installed the problem went away.
 
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My idea is to deliver small batches of top quality products. The quality which cannot be achieved in any top quality mass produced items. I mean I try to improve the best PCPs out there for myself and I share my work with others.

As an example - each of the delrin disk was manually polished to achieve the smoothest surface possible. Then each one was verified under magnifying glass. There is no way each part can be verified like that at the factory which produces hundreds and thousands of parts.
 
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I finally installed my new pistons last night. I got myself a little confused at one point, but I'm new to airguns so that is par for the course. Overall the install was super easy and I'm a little annoyed with myself I waited so long to do it.

I'm currently shooting 18.9gr JSBs. .22 caliber. Reg settings are 115/86. Pretty sure I have the lightest hammer weight in there, but haven't weighed it just yet. 600mm barrel.
Speeds between 910 - 940. (I've struggled a little with ES with this gun though SD has been more reasonable.)

Result?
The plenum refreshes faster and quieter. It used to really gasp, now I can barely hear it. Refresh time "feels" close to cut in half.

I shot two magazines so far. Out of those the last 21 shots looked like:
1) 926
2) 932
3) 912
4) 919
5) 930
6) 930
7) 930
8) 930
9) 932
10) 930
11) 932
12) 921
13) 935
14) 932
15) 919
16) 930
17) 930
18) 932
19) 930
20) 932
21) 930

Obviously a few stragglers in there, but some of the best consistency I've seen so far, and the pistons haven't had a chance to settle.
No reg creep overnight.
I need to work on the tune a little, but the gun is shooting sub MOA at 50 yards in the rain.
I will be switching over to .30 caliber very soon, and am excited to see how the gun performs at the higher output.

Thanks for the great product @Seeker !
 
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