Short Stroking M1

[119er]

I have an M1 that I bought at a gun show (I know) that has been rebarreled with a Criterion barrel and completely reparkerized with new wood that fits nice and tight. The first few rounds through this rifle functioned correctly. I'm using Federal's American Eagle M1 rounds. Since then it fails to feed reliably. Doing a search here yeilded a cracked gas plug which I replaced. Today I fired two clips through it and the first 8 rds had to be cycled manually. On the second clip 1234 were manual, 567 fed themselves, and 8 was manual again. Here is what I know/verified.

Gas plug is good
Gas piston mic'd a little ovate or flat sided @ .525 x .523
Gas cylinder looks okay, but I can't measure the Bore where the piston rides. Exception being that the bayo lug is beat up where someone drifted it off.
The rifle passes the tilt test very easily
The man I purchased it from said he chambered the barrel very tight
Gas port is not plugged or restricted

Please help me fix my short stroke!

Information

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[Bob Womack]

There have been many posts on the subject of commercial ammo in the M1 Garand. With the exception of Hornady's target round designed specifically for the Garand, my last understanding was that there wasn't any commercial ammo that functioned well with the Garand without an adjustable gas plug. You can read some of the opinions HERE. The upshot of the problem is that modern power formulations burn too quickly, throwing off the timing of the Garand's gas system. A possible result can be a bent Op Rod. This can be ameliorated by the use of the adjustable gas cyllinder lock screws. There are two both available from Brownells, Shuster and McCann. The basic technique is to install the plug, open it up 'til the action doesn't cycle, then slowly adjust it down to where the action just cycles reliably.

Most folks stick with milsurp ammo (available from the CMP Store) but the adjustable plug gives you an option.

Of course, there could be other reasons for the problem.

Bob

[119er]

Thank you for the links. That said, the ammunition sold for the M1 Garand is not suitable for use in the Garand? I will say that the recoil felt different at times with it being the heaviest on the rounds that cycled correctly. Maybe I'll just wait to get my dies to continue to test function. I thought that factory ammo would be the best option for break in and baseline for operation.

[Bob Womack]

I wasn't aware that Federal was putting out a Garand load. Sorry about that. Around this board, most people suggest running milsurp ammo as the baseline when calibrating the rifle. I really don't know the characteristics of this round other than the fact that it has a 150 grain bullet and 2740 fps at the muzzle. However, I can tell you that the lowest price I found for it online was $19.95 for 20 rounds. That's a buck per pop. The Greek ammo from the CMP averages out to $0.53-0.54 per shot - right around half that. I wonder if the Federal primers are tough enough to handle the semi auto action? If not, there's the possibility of the firing pin firing it when the bolt slams home. Surely they thought of that when they spec'd it for the Garand, though. Hopefully someone better acquainted with the problem will wander by soon!

Good luck,

Bob

[119er]

I will have to get registered with the CMP. I bought the Federal ammo as a crutch to get by until I begin to reload. It is hard to determine what the condition of the op rod because of the refinishing. The rod looks perfect, but the piston shows some age. I was wondering if anyone has gotten similar measurements on theirs before. Or possibly knows what the inside dimensions of the gas cylindeer should be. Mine has obvious peening with scratches and gouges, but it fits very tight to the barrel. The problem seems to be in my opinion, a loss of gas pressure. The ammo may not be the genuine article, but it is loaded to mimic it. My next step will be either new cylinder or repair/replace the op rod. The latter being the least desireable. I know each rifle is it's own animal, just hoping someone had a similar experience!
As a sidenote, there was a gentleman at the range that said it is possible to braze brass to the piston and turn it down to size to allow the brass to be the bearing surface. I would rather avoid things like that, but does it hold water?

[browningautorifle]

Don't be fixin' your own piston. Your CMP has that sort of thing I think. They are available to you anyways. There's lots of them right here on this forum. I haven't gotten involved until now because we go through this every week here. This whole thing is here in the M1/M14 forum and there is a sticky for stoppages of the M1. Yes, there's a proper inside dimention for the gas cylinder and an outside measurement for the piston. I agree that one of these is to blame. I don't think it's the factory ammo because this particular load's marketing position was "To be used in the M1". I just wonder, you had no problem until you changed the gimped gas cylinder lock screw? Why can't that be at fault again? New parts aren't always new, maybe just refinished.

[119er]

The rifle has never functioned correctly since I've had it. In my efforts to find the problem I found the cracked gas plug. I replaced it to no avail. Maybe a marginal improvement since it cycled itself a few times after replacement. I see this as further evidence of blowby. I am a newbie and was just asking in the hopes that there was a clear answer. I guess it is just because I bought this particular rifle on an impulse, at a premium price, and I want to minimize the amount of $$$$ I'm throwing at it! I bought it from an individual as well, so there is little to no recourse.

[browningautorifle]

True, maybe a new OP rod and gas cylinder will do it. I should think so. Just be careful of your source and let us know how this develops. The beauty of these rifles is that they CAN be rebuilt easily.

[Garandy]

If your op-rod piston is undersize as you say, ship your op-rod off to Columbus Machine in Ohio and have a new one installed. Much cheaper than a new operating rod. Maybe you can get lucky and find someone local with an M1 gas cylinder gauge so you know where you stand in that regard. Since your barrel is a commercial replacement, have you verified the diameter of the gas port in the barrel? Is the gas port obstructed at all when the gas cylinder is installed?

[Charlie59]

You should have a piston gauge, and a set of cylinder gauges. You can sell them when you're done, or keep them like I did. I save $150. on an oprod, thanks to my gauges. I've never had trouble with Hornady or Federal M1 ammo, but I refuse to pay those prices. I suggest completely going over your parts, in case something else has been buggered up, and making sure your rifle is properly lubricated.
Charlie

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