GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: skiron on May 13, 2018, 03:30:51 PM
-
Just bought a Prod and this is my first tune with it...Guys, this thing is sooo easy tunable...pure enjoyment! :)
Mods:
- end to end porting: @3mm
- stronger hammer spring: 1.25mm wire, 9mm OD, 40mm free length, cutted from 45mm initial (open up the hammer hole a bit to fit th OD)
- 3 O-rings inside valve tube (Bstaley mod)
- ZERO hammer spring preload (this tune is for best consistency, but I have all my preload turns available in case I need more power)
- Max hammer stroke length
- 3500 psi fill (this is 2.7:1 safety margin - max pressure for failure (no hard failure, screw heads not to shear off) is @9500 psi.
*3500 psi is well above maximum recommended 3000psi from Crosman, but 2.7:1 safety margin is not bad with some precautions: 1) 3500psi fill will be used only for short intraday hunting sessions 2)CAREFYLL OBSERVATION OF 3 VALVE SCREWS for any kind of deformation (screws are 8-32 x 3/16” high strength alloy steel,with low profile and socket head) 3)Storage below 3000psi
Shot string with H&N Piledrivers 29.17 grain
Shot# FPS FPE PSI
1 571,30 21,1 - 3500psi
2 570,00 21,0
3 575,30 21,4
4 567,80 20,9
5 575,30 21,4
6 579,50 21,8
7 575,90 21,5
8 581,40 21,9
------------------------
9 578,90 21,7
10 578,40 21,7
11 582,30 22,0
12 588,80 22,5
13 585,40 22,2
14 585,10 22,2 - 3000psi
15 583,10 22,0
16 582,30 22,0
------------------------
17 579,70 21,8
18 584,20 22,1
19 577,00 21,6
20 576,40 21,5
21 578,10 21,7
22 572,30 21,2
23 576,70 21,5
24 569,60 21,0 - 2400psi
AVG FPS of 24 shots: 578.1
AVG FPE of 24 shots: 21.7
Extreme spread of 24 shots: 21 fps = 3.57%
(shot some more shots that didn't take them into account (stayed in 3 clips total) but here they are regarding fps:
574
572,1
562,5
555,8
556,5
553,5
548,2
537,2
*I was able to produce max 35,1 FPE (736.10 fps with piledrivers 29.17grain @3500 psi), with same spring before cutted (45mm), without the 3 o-rings mod, and with no hammer spring preload, but only for a few shots, so tuned down. With some spring preload it would produce some more but no need for so much power unless I instal a second air tube for some descent shot count. Anyways, with an allen key, I can tune up a bit from where I'm standing now, in case I need more power in the field.
Conclusion: just 1 hour of working with the gun, and the result is pretty good from my point of view...21-22 fpe for 24+ shots and with an ES of 21 fps (3.57%) only... I'm gonna fall in love with this little @$%^ for sure! :)
best,
Argyris
-
This was with mine turned up almost all the way with the present tune, I could always get more but I figure why cause it's just shooting so darned good the way it is. I have the TSS on it backed all the way off and I'm getting about 13 shots at 30fpe right now with the JSB18.13's in it. It's really all I need when I'm out hunting with this gun.
(https://farm5.staticflickr.com/4659/25384290517_72f16a02f5_b.jpg)
-
Nice, want to do a prod build myself one of these days. Be a great Hunter for my area.
Using the stock barrel?
-
Mine is the original barrel, well broken in and just ready for the kind of mods I did on it. Darned good barrel if I might add ;D
-
My barrell is the original too and is able to take down starlings at 45 yards and more,so i call it accurate for pesting ;D