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Alan Alford's build

2250b Tube for later move to bulk CO2.
12" .22 Caliber Barrel from Doomsday Backpacker
Brian & Assoc. Alluminum Breech with 2 barrel screws
Original site rear
Pin site on Custom Mt. Airguns Muzzle Break
2x1 Centerpoint Scope with UTG dovetail adapters
Mountain Airguns Custom Bolt and Handle
Mountain Airguns Custom Power Adapter and spring guide
B&A Boss Valve for extra Power

Built mainly for fun and to shoot at local Field Trial Pistol Match.

It currently it shoots a 14.3 Crosman Hunting Pellet at about 530 fps in a 72 degree room for 8.92 FPE.



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AS2250XT headaches

September 26 2011 at 2:07 PM
Mark  (Login Specman)
Crosman Forum Member
from IP address 85.211.131.114

OK stock XT in .22 was shooting 8.2-8.5ft/lbs pre mod

Fitted a .177 barrel, port and barrel standard mods kept valve standard and I was getting 8.29ft/ps 596ft/psec with crosman 10.g

Fitted a lighter valve spring to the mix power drop to 7.52ft/lbs

Getting leaks through the barrel after around 12 shots, swapped out valve stem and modded and shaped new one power still 7.52ft/lbs

Fitted standard hammer spring (to fix leak) and fitted lighter valve spring power dropped to 5.14 - 5.71ft/lbs 548-578ft/per sec.

Oh man...What's happening!!! Co2 leaking again through the barrel after about 20 shots, breech blow back from faulty probe.

Groved my hammer to prevent sear drag, fitted standard valve stem and standard spring but heavier hammer spring. fixed/replaced probe. Velocity is now down to 5.7ft/lbs 578ft/per sec but the valve completely empties with one shot (when I turn off the CO2, which is good right?)

So its back to the drawing board. I'm opening up the valve but its apparent that spring balance is critical in the AS. I'm going back to the standard hammer spring and lightening the standard valve spring.

Any thoughts as to why my velocity is dropping consistently shot on shot? Is it temperature?

The AS is a lot harder to get right than the 2250b
Cheers
Mark


    
This message has been edited by Specman from IP address 85.211.131.114 on Sep 26, 2011 2:07 PM


 
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