SVT-40 Gas Piston Removal

Have a SVT-40 with a gas piston that does not want to come off. Yes I have a Soviet-era wrench for it, but I am hesitant to apply too much torque lest the head of the piston snap off like an old bolt. There have been extended periods of kroil, but so far no luck. I am hesitant to shoot it because this is a non-rebuilt gun with an early stock with the thin wrist that has already had cracks repaired. I can leave it as-is if it comes to that but would prefer to get the piston loose so as to properly clean that area of the gas system and leave the gun a little better off for whomever owns it after me.

Suggestions appreciated, even though I'm guessing there is no magic bullet for this one.

togor: I routinely use a longer wrench than the original Soviet tool to break loose tight ones. The pistons have quite thick walls and unless very badly corroded I can't picture one breaking unless a very large amount of torque is applied. I would set the front sight base up in a vice with brass blocks so that you can get some good torque applied to the piston. You could also heat up the gas block with a good hot air gun (I doubt you'd want to risk the finish with a flame). Only you can judge if you need to give up trying to get it off but, if it were mine, I'd make a maximum effort as there may well be active rust in there. On another note, when you say the stock has been repaired, do you mean the standard Soviet method with pins through the wrist?

Ridolpho

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Originally Posted by Ridolpho

togor: I routinely use a longer wrench than the original Soviet tool to break loose tight ones. The pistons have quite thick walls and unless very badly corroded I can't picture one breaking unless a very large amount of torque is applied. I would set the front sight base up in a vice with brass blocks so that you can get some good torque applied to the piston. You could also heat up the gas block with a good hot air gun (I doubt you'd want to risk the finish with a flame). Only you can judge if you need to give up trying to get it off but, if it were mine, I'd make a maximum effort as there may well be active rust in there. On another note, when you say the stock has been repaired, do you mean the standard Soviet method with pins through the wrist?

Ridolpho

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Hi Ridolpho,

Kroil and hot/cold have been applied, so far without the piston coming loose. More of the same may take a long time, but patience is necessary. The gun is slightly unusual, an all matching, non-rebuilt piece. Even the stock matches, although at one time bubba slathered some varnish on it after sanding it down a bit. Rick Borecky did some extensive glue repairs at the wrist and forearm.

But it is a war veteran and the metal is in good original shape. So to complete the project I'd like to fully service the gas piston, if possible, and figure out what to do about the stock finish. Original Tula '41 finish is long gone, so now it's bare wood on the exterior (although the wood still has the asphalt smell). I may just use a few coats of raw linseed oil and call it good at this point. Unless someone has a bottle of VK-1 they don't need.