More reliability out of SVT40 gas system

adriel

adriel

CGN Regular
Rating - 100%
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Location
Edmonton
Thought I'd share, because this was driving me up the wall and I'm really happy to have it pretty much resolved.

Even at 1.7, my SVT40 was not confidence inspiring. It'd short stroke and fail to pick up a new round or the bolt would barely come back and wouldn't have enough spring tension to strip the next round from the mag without jamming it nose first just below the chamber. The loaded round stovepipe would happen as well. All told, I'd get 2 failures from each mag, and the bolt hold open would always fail.

Looked around for some solutions, found some dude who sells new stainless piston/cup plus springs for the SVT40, and picked up and installed both. My piston/cup weren't awful, but were a bit sticky in some orientations and the inside of the piston looked like hell. New reliability stats out of 50 rounds fired: 1 loaded round stovepipe, no short stroking or new round jams, 2 failed bolt hold opens (out of 10.) I can deal with the failed bolt hold opens, the much reduced failures to load have me very happy. 2 fewer critical components to worry about rusting together after shooting corrosive too.

all-parts.jpg


More info here: http://www.huntinggearguy.com/equip...inless-cup-piston-aftermarket-recoil-springs/
 
Try new ammo and see how it works it just might not like the ammo your using.

You can also adjust the gas system as well seems that it needs to be opened up for the ammo your using.
 
My first time out, the piston was loose and the gas port rotated with recoil, causing issues. I take that first outing as a bit of the learning curve of owning an SVT40 and afterwards familiarized myself with the breakdown and gas adjustment. Cleaned the gas port and holes. After I got that straightened out, I've gotta blame the piston/cup combo. It's not bad when it's exactly 0 degrees and lined up, but with this kind of system, a bit of angle is to be expected, and it feels like a lot of resistance with just a bit of angle. Tried light ball Bulgarian surplus, MFS 185 and MFS 203. The gas piston looks ok, but just isn't as low resistance as the stainless parts. I could be wrong, and it could be wear-in on parts, but after 300 rounds of surplus ball ammo, it's unlikely that it's got enough wear in that it all of a sudden decided to start flying straight and narrow. I could run a few hundred rounds more, but making it through a few stripper clips without fail made me so relieved about this rifle.
 
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