M1 Carbine gas piston

[eb in oregon]

I'm well aware this topic has been beat up, tossed about, argued about, and discussed numerous times, but it bears mention again.

I've owned and shot M1 Carbines for over 45 years. My first rifle purchase after finishing my first tour in the Army in 1974 was a Plainfield carbine. It was identical to the military carbine except for a birch stock with a plastic butt plate and it worked flawlessly. Until it was stolen during a home robbery when we were at work over 30 years ago. However before it was stolen I'd experienced gas pistol/cylinder problems from shooting quantities of lead bullets in it. One day it just quit working.

I found the gas piston stuck in the extended position and it wouldn't budge. Disassembling the piston (I've a set of armorer's wrenches and tools) I found the gas cylinder packed with lead. It took some careful work to carve it out without scratching the bore. Once that was done it worked like gang busters again, up until it was stolen.

But then last year I was shooting with my older brother and he was shooting his M1 carbine and it was having functioning problems. I brought the carbine home, disassembled it, and found the gas piston stuck in the extended position. The gas cylinder was full of bits of lead, thus rendering the piston's function inoperative. I cleaned it and reassembled it and test fired it. It worked like gang busters.

So, the other day I was cleaning another Plainfield I'd acquired a few years back after firing it after it had been sitting for a couple of years. The piston was stuck and refused to budge after removing the piston nut. Not wanting to damage anything I cruised the internet for an hour or so looking up the subject. One guys post said "If it works don't mess with it." So I put it back together and fired three rounds. It worked perfectly. So I took it apart again to find the piston still stuck. This really bugged me so I took the nut back out, reassembled it, and fired one round with a magazine with a bolt stop follower. The gas piston was found inside the stock, no damage anywhere.

I found a "coin" of lead at the bottom of the gas cylinder, along with some nasty carbon. So I carefully carved it out and cleaned the gas cylinder removing all lead and carbon. What was happening is that when firing the piston would do it's job but when pushed back in by the slide it would stick to the lead thus capturing the piston. While it worked before the question is "for how long?" Having lead and carbon in the gas assembly is a bad thing. It gums up the works, has nowhere to go, and will stay within the gas cylinder until it is cleaned out as described.

So, I've had three carbines I've worked on for the same issue, which is the heart of the M1 Carbines function. The very first time I encountered the problem I stopped using lead bullets in my carbine. The Plainfield I now have I've shot nothing but jacketed bullets through it, so whoever owned it before me shot a bunch of lead bullets through it. My brother had shot lead bullets in his, bullets I'd given him. While many people shoot lead in their M1 Carbines I'm convinced it's not the best thing to do as it blows small bits of lead into the gas cylinder and eventually they will have this problem. I myself don't want to make disassembly of the gas assembly a part of normal maintenance so I'll stick with jacked bullets.

This is only for informational purposes, I'll not tell anyone what they can or can't shoot in their firearm, but it is information that could save heartache for others in the future.

Information

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