My Marauder Pistol (Prod) 22 fpe - 24 shots Tune

[skiron]

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

[Wayne52]

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.

[sawtoothscream]

Nice, want to do a prod build myself one of these days. Be a great Hunter for my area.   

Using the stock barrel?

[Wayne52]

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

[Tucobenedicto]

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