What exactly did I just buy? how to handle a cracked gas piston assembly?

Looks like about everythings been covered on your Underwood. Sorry about the gas cylinder issue. It's not something you see on carbine barrels a lot, but they are out there. The rear sight is also unfortunate, but not a s bad as the barrel issue. I have seen more than a few Bavarian carbines that had the rear flip sight messed with. This is one of the first though where the sight was put in backwards. BTW, have you found any additional Bavarian markings, if it is one? If you are going to sell or part it I'd be intrested in a few things, mainly the stock if it's as nice as your pictures depict. Let me know, thanks.

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Originally Posted by vintage hunter

Don't even consider it. I'm afraid that ''gunsmith'' is just blowing smoke hoping to scam you out of some $$. I agree with what others have already said, get your money back and find another one with no issues.

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Yeah, I'm taking it back. Thanks for pointing out the backwards rear sight. After seeing carbines on Gunbroker, this one has more issues that i want to deal with. BTW, the store were I bought it has a 30 day return policy for firearms which is pretty much unheard of. Their return policy is the only reason I bought the gun in case someone was really wrong with it, and in this case, there is way to much wrong.

The gunsmith (at the store) is one of the best and most knowledgeable people I've worked with. He was more than willing to do the repair free of charge. In fact, the store policy is to try to make it right if the customer wants it fixed. I did see in other forums where TIG welding was suggested but never saw a response where someone actually did it. Considering the buggered up nature of both sights, I imagine that the same knuckle head probably cranked on the gas piston nut until the gas assembly cracked. A barrel replacement is too expensive. By the time I invested money in a barrel, I might as well buy a decent CMP or NRA gun in much better shape. The excellent condition of the bore sucked me in; the other issues blew me right back out. At least I'll get my money back. I actually have a pretty extensive collection of milsurps, but this was my first M1 carbine. Lessons have been learned!

Thanks for the immediate responses.

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Originally Posted by deldriver

Looks like about everythings been covered on your Underwood. Sorry about the gas cylinder issue. It's not something you see on carbine barrels a lot, but they are out there. The rear sight is also unfortunate, but not a s bad as the barrel issue. I have seen more than a few Bavarian carbines that had the rear flip sight messed with. This is one of the first though where the sight was put in backwards. BTW, have you found any additional Bavarian markings, if it is one? If you are going to sell or part it I'd be intrested in a few things, mainly the stock if it's as nice as your pictures depict. Let me know, thanks.

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I didn't see any other Bavarian markings. I saw on other postings on various sites that some carbines didn't many markings, but at this point, I have to assume that might just be a "correct" mixmaster considering how so much is wrong. I afraid that I'm not going to be able to part it out. I have to return the whole gun in order to get my money back, and I'm afraid that I don't have enough patience to try see it piece by piece. Maybe I shouldn't write this down, but there is a brand new Remington 700 5R in 308 Win that calls out my name every time I walk by it.:) Or I might just wait for the right M1 carbine....

Keep an eye on the CMP forum sale section, usually some good deals on quality carbines there. If the store give you some grief show them this thread!!

M1 Carbine - CMP Forums

The gunsmith can say the welding will work but it won't. It's a high stress point. The government even gave up on trying to get cracked gas cylinders welded or brazed and none of the attempts worked. The only fix is a new barrel. Most all of the cracked gas cylinders are due to someone over tightening the castle nut and causing the cylinder to crack. It is very rare that a piston or gas cylinder needs attention to the point the nut has to be removed and the piston removed. That is why only ordnance people were issued the proper wrench to remove the castle nut.

There was a producer of 19" barrels that welded their gas cylinder on and didn't harden things right, or took the temper out when welding it. They stretched and let the piston and nut go and there was nothing to be done about it...

Mine's in good shape so I'm not shooting it any more. That would be disastrous esp. when you have the original barrel/receiver.

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Originally Posted by vintage hunter

Don't even consider it. I'm afraid that ''gunsmith'' is just blowing smoke hoping to scam you out of some $$. I agree with what others have already said, get your money back and find another one with no issues.

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I have heard of some folks trying this with various degrees of success. Best case scenario is that it will turn out to be a temporary fix.