Checking the headspacing on the M1 Garand


April 22, 2003, 09:42 AM
My Garand is ripping the rim off of cartridges, causing a failure to extract. I suspect my headspace is wrong. Is there a way to check it without the field gauges, and how does one go about fixing it?

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April 22, 2003, 01:17 PM
What powder are you using? The Garand is sensitive to powder burning rate & peak pressure timing, too fast or too slow a powder and you can rip the case rim off.

April 22, 2003, 03:45 PM
What am I not using? Yugoslavian, S&B, American Eagle, Danish, Remington... every type of ammunition has the same problem.

April 22, 2003, 07:29 PM
Clean and check your chamber, also. A rough chamber can cause hard extraction and cause case rim to fail. Chamber should be cleaned using a chamber brush w/copper bristles, then lightly oiled patch and check for pitting.

You might also inspect your extractor, but rought/dirty chamber is more likely.

The garand was designed to handle M2 Ball or M73 match ammo, can't remember designation of the AP round, but bullet weight on it was in the neighborhood of the M73 which uses 173 gr. bullets. I would not use anything heavier than 150-175's as heavier bullets require slower powders. 4895 is an ideal powder for the M1 as anything much slower while producing safe breech pressures will develop too high pressure at the gas port and cause damage to op-rod. Never shoot the new "light magnum loads" in a garand.

Various M2 ball equivalent loads are commercially available. PMC makes one and there are several surplus rounds suitable. Have heard the Danish is good if you can find it. CMP had some, ran out and I think have obtained another lot of suitable ammo for the garand. Try


Jim K
April 22, 2003, 11:02 PM
I agree with hps1 that the problem would not seem to be headspace. Stick to military ammo specs and try his cleaning suggestions, but if it still doesn't work, the problem may be more serious.

Where did you get the rifle, and has it been worked on? Does it have the original barrel? Is the op rod spring the right length and tension? A rusty chamber is one possibility, another is an oversize gas port causing the rifle to open under high pressure.

It is possible that an adjustable gas cylinder lock screw may solve the problem if it is a large gas port, or you may need a new barrel.


April 23, 2003, 05:23 PM
Thanks to those who have replied so far. I'll elaborate on my weapon.

1. The chamber is squeaky clean.
2. The barrel is not original. My researchs shows that the receiver was made in 1943 and the barrel in 1951. I hope :D that the replacement was done by a US mil armorer.
3. The gas port does not seem to be out of spec.
4. The op spring is a brand new replacement; it is the same length as the old one. My problem has spanned both springs.

I am probably going to send it to Fulton Armory and let them deal with it.

Sleeping Dog
April 24, 2003, 12:35 PM
If you shoot the gun without the gas plug, it will act like a straight-pull bolt-action. It might help to see how easily it extracts the case when you pull the op-rod by hand after the shot. And what condition the case is in without the mangling power of the gas operation.

Then, I'd look up the number for Mid-County Firearms in Oak Harbor, OH. The proprieter used to be an armorer for CMP. His shop's about 5 miles from Camp Perry.

Or, go to and ask about smiths in your area that know M1's. That site is pretty active with M1 enthusiasts.


April 24, 2003, 02:19 PM
I was going to start a new thread on this, but since you mention straight-pull operation here I'll ask here.

What exactly do you need to do to properly convert a Garand into a straight-pull bolt action? My guess is:

A. Remove the gas cylinder and handguard.
B. Cut and recrown the barrel below the gas port.
C. Cut the op rod and spring down so they don't extend past the stock, welding a new cap on the op rod.
D. Epoxy or weld your preferred front sight to the shortened barrel, or mount a scope.

Did I miss anything? If not, can I skip step B or will it act like a reverse muzzle break?

Jim K
April 24, 2003, 09:41 PM
Hi, Devonai,

That is quite a job. All you really need to do to convert to straight pull is to buy a valve type gas cylinder lock screw and drive or drill the valve out. Or buy one of the junk slot type repros and just drill a hole through it (don't do this to an original slot type, please).

If you remove the gas cylinder, you will have to rig up something to support the front of the op rod. What you propose would be irreversible without spending a lot of money if you change your mind, and I think it would be unsaleable as modified.


April 24, 2003, 10:07 PM
I'm quite aware that the modifications would be permanent. If you could get away with only modifying the op rod and spring, you could cut inexpensive replacements and save the originals. The real point of the conversion is to save as much weight as you can versus the original rifle. I do not intend to permanently modify my Garand, which is why I'd skip step B if I did it.

I also think that if something is interesting enough, eventually someone will buy it. An expertly done conversion with a custom stock and scope mount would probably bring a nice price.

Sleeping Dog
April 25, 2003, 08:59 AM
When I convert my M1 to straight-pull, I just swap gas plugs, I have an extra that's drilled (1/8").

I don't do it to cut rifle weight. Mostly it's for playing with heavy bullets and slow powder, and I don't want to stress the op-rod or other mechanisms.

It is not, I repeat NOT, because I'm too lazy to walk all over the place picking up spent brass, no. :)

It just seemed like one more tactic to try to find out what's ailing this M1 with the hyper-extraction problem.


Jim K
April 25, 2003, 11:56 PM
I have seen a few M1 rifles "sporterized" much as you describe. Some were essentially the same idea as "tankers" except with a slightly longer barrel and a sporter stock. One I saw had a nice checkered walnut stock with a high comb, rear sight removed, an offset scope, and the gas piston inletted into the fore end. Polished and blued, it was a nice job. I forget what the price was, but it sat at a dealer's for a couple of years, and was still there when he went out of business. I don't know what happened to it.

As to converting to straight pull rifles, it is pretty common in states where semi-autos are not legal for hunting.


Sleeping Dog
April 26, 2003, 08:07 AM
Jim, does screwing in a drilled gas plug make the gun legal in bolt-only states? It's an easily reversed "modification".

My state allows semi-auto, with a five-round magazine limit. So we have funny enbloc clips that hold five in one end, or turn it over and it holds two.


Jim K
May 5, 2003, 11:15 PM
I have known several people who used them in PA with drilled screws. AFAIK, it is legal as long as you don't have a regular screw in your pocket. Some folks have suggested a switch of some sort on the plug, but I have no doubt that would be illegal since you could just "turn on" the semi-auto.

I suggest, though, that you check with the current laws before going hunting, and write the state game commission with any questions. The papers always report new "gun control" laws, but almost no one pays attention to changes in the game laws which can get a person into as much trouble.


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