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.

[george r]

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.

Back when I was in high school a friend of mine formulated the rule of Levitt: If you are forced to solve a problem and you don't know what you are doing replace the cheapest thing first in your experiments. Did you disassemble it and clean and lube it when you first got it? It could just be gummy from disuse. Try swapping out the op rod spring. If you can't borrow a good one then clean and stretch the one you have a tad. If you haven't taken it apart already you may even find the spring is in pieces. Anyhow the spring is what operates the gun during the load cycle. Its hard to tell from your post if its failing to pick up a round and closes on an empty chamber or it fails to chamber a round it has picked up. Also with the spring out reassemble the mechanism and the wood and see if the loading cycle is hanging up on something by operating gently it by hand. Put the spring back in before firing it.
Also, try this: M-1 Garand tips accuracy improvements - Detroit Firearms | Examiner.com

[campperrykid]

Some other factors that might be worth checking:

Gas piston diameter 0.525 min. ( seems like your piston is smaller. )
Gas cylinder internal : 0.532
(From Duff's book, M1 Garand Owner's Guide , very good to have)

Try putting a piece of tape on the piston , measure it with a mic , and use it for a crude gas cylinder guage . It is not ideal , but better than nothing.
A tight chamber can complicate function .
What kind of lube are you using & where?

[119er]

I completely disassembled, cleaned, and lubed the rifle following the CMP website for lubrication. The bolt will travel rearward with enough force to eject the empty case 4 to 6 feet away from my position, but closes on an empty chamber. When empty, it takes extra effort to lock the bolt rearward once it reaches roughly the last 1/4 to 1/2 inch or so. When loaded this diminishes somewhat. Also, on the last round fired it ejected the case but not the clip. I'm going to get some measuring tools and get it figured out.