M1 Rifle short stroking


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Owen
February 18, 2006, 04:26 PM
I have a CMP Garand that is short stroking on the first and second round from the magazine. I am shooting Korean M2.

Any suggestions?

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dfariswheel
February 18, 2006, 07:12 PM
Replace the recoil spring with a new, ORIGINAL power spring.
NO "extra power" springs.
Worn recoil springs are the #One cause of short stroking.

Check the gas system for:
Loose gas cylinder lock screw.
Leaking gas, which will show up as soot around the lock or around the barrel.
Check the gas cylinder to insure the gas port in the barrel is properly located in the gas cylinder "window". (In other words, is the gas cylinder mis-aligned too far forward or too far back).

GREASE the rifle. On the M1 oil is a rust preservative. GREASE is the lubricant.
Check a manual for the proper areas to apply grease.

Clean the chamber with a GI M3 combination tool with the chamber brush. Make sure the brush is good. Old brushes or brushes someone's wrapped a patch around are no good and won't clean properly.

Gage the op rod head and the gas cylinder for undersized head or over-sized cylinder.

Do the "45 degree test" to check for binding.
Disassemble the rifle and remove the recoil spring, leaving the bolt in place.
Tip the rifle up and down 45 degrees.
The op rod and bolt should open and close on their own.
Without the recoil spring, reassemble the rifle into the stock without the trigger group.
Check again.
Again, the op rod and bolt should open and close on their own weight.

Try different GI spec ammo.

MechAg94
February 18, 2006, 07:29 PM
Which book is it that everyone recommends to get? Is it by Duff?

Dienekes
February 19, 2006, 01:38 AM
For excellent technical and gunsmithing stuff, Kuhnhausen's book on .30 Cal. Service Rifles. Hatcher's Book of the Garand is old but very good and I refer to it often. There are others but I find these sufficient.

Trebor
February 19, 2006, 06:12 AM
Replace the recoil spring with a new, ORIGINAL power spring.
NO "extra power" springs.
Worn recoil springs are the #One cause of short stroking.
.


Exactly what I was going to say. I agree with the rest of his advice as well. The good news is that a recoil spring is a $5 part.

mustanger98
February 19, 2006, 02:55 PM
Starting out, I had a short-stroking problem with my Garand... I replaced the op rod spring with a new one from Fulton Armory- $5 as mentioned. I did the 45degree test too. I also found the gas nut would loosen up, so I check that and tighten it with the wrench which is on the M3A1 combo tool. Works fine, but if too much gas is blowing around the piston, that another problem hence mention of guaging those parts.

Chris Orndorff
February 19, 2006, 02:56 PM
I understand "short-stroking" to mean that the bolt does not travel fully to the rear during recoil. How then does a worn recoil spring help? Seems a worn spring would allow the bolt to travel rearward more easily. Thanks.

mustanger98
February 19, 2006, 03:05 PM
I understand "short-stroking" to mean that the bolt does not travel fully to the rear during recoil. How then does a worn recoil spring help? Seems a worn spring would allow the bolt to travel rearward more easily. Thanks.

The worn spring doesn't help. The recoil spring is serving two functions at once- cycling the bolt, and pushing the magazine follower arm up so as to position the next round for feeding. To do that, it has to have enough tension. The actual short stroking can be a combination of small problems like the spring tension not being right, plus an out of spec gas cylinder or piston. Or it may just be that the gas nut is loose and needs to be tightened so it doesn't bleed gas out the front end instead of cycling the op rod and bolt.

Knowing what I know now, which I didn't know to begin with, I'd check the gas nut to be sure it's good and tight. Then shoot it and see if it acts up again. If that don't solve it, like I said, replace the op rod spring with a new one (I've heard of some people thinking the spring was too long and shortening it and that causing problems) and guage the parts.

dfariswheel
February 19, 2006, 03:06 PM
Ordinarily that might be true, but the M1 is a "special case". It works differently than other rifles.

The op rod spring doesn't just power the op rod, it powers the entire feed and timing assemble.

Trust us, short stroking is often caused by a weak spring in the M1.

Chris Orndorff
February 19, 2006, 03:13 PM
Trust us, short stroking is often caused by a weak spring in the M1.

I'm not doubting anyone, just trying to understand. Does the same hold true for the M-14/M1A?

mustanger98
February 19, 2006, 03:34 PM
Not having dealt with M-14's, I have no experience to say whether this would be a problem for them. However, with the M-14/M1A, you don't have the whole linkage between the op rod and feeding system as on the Garand. I do know from conversations with vets that you do have to watch the gas nut on the 14 and be sure it's good and tight or it will short stroke.

Owen
March 6, 2006, 01:59 PM
OK, I've done everything except the spring, I have one on the way.


I did notice that it I remove the gas cylinder, but leave the op-rod in place, the end of the op rod is centered on the gas port. Is this normal?

Owen
March 16, 2006, 09:40 AM
OK, I got the Garand spring kit from Fulton Armory, and replaced all the springs except for the ones in the bolt.

Now, It short strokes after the first four or five rounds. :confused:

MechAg94
March 16, 2006, 09:56 AM
I bought a 2nd hand CMP rifle several years ago. It was short stroking on me from the start. I looked at it of and on and had other rifles so it wasn't a priority. Anyway, I was looking at it with my Dad and we noticed tne Op Rod was bent. It was difficult to see if you are a newb and didn't know to look for it. Replacing that improved operation a good bit, but it still wasn't reliable 100%. Anyway, I recently learned to use the grease properly after I bought a CMP HRA Garand, and I got a couple of those 17-7 op rod springs from Sarco. I shot several clips of Korean PS ammo last weekend with no problems whatsoever. I think those two things were the last pieces I needed.

The best I could say is to pull it out of the stock and operate it manually with and without the spring looking at all the moving parts. I bought a spare gas cylinder when I was trying to troubleshoot. I don't know if they are cheap anymore.

Does anyone have a link to the gas cylinder gauge specs?

ocabj
March 16, 2006, 10:50 AM
http://www.fulton-armory.com/ShortStroking.htm


# reloads
# improper headspace
# rough chamber
# bad gas cylinder
# bad op rod/gas piston
# Gas port undersized
# leaking gas cylinder lock screw (gas plug)
# improperly located gas cylinder
# severe op rod binding


The next things I'd check would be gas cylinder, op rod, and gas plug. Do you have spares? Or can you pull ones of another rifle to test?

I try to keep extra parts around for my Garands. Unissued gas cylinders, verified oprods, springs, extractors and ejectors, etc.

Owen
March 16, 2006, 11:11 AM
I don't have a spare op-rod or gas cylinder.

I don't have a means to measure the gas cylinder, although the piston checks out ok. I don't have a .30-06 headspace gage set.

The oprod doesn't seem to be binding anywhere. Without the op-rod spring, it shuttles back and forth at about 35 degrees of inclination.

I'm starting to think I need to send it on a trip.

30Cal
March 17, 2006, 12:32 PM
Take a careful look at the face of your gas plug. They have been known to crack from time to time.

Ty

loadedround
March 17, 2006, 12:42 PM
Mamy times your gas cylinder plug loosens up and backs out causing short stroking. Make sure it is hand tight.

mustanger98
March 17, 2006, 02:48 PM
Many times your gas cylinder plug loosens up and backs out causing short stroking. Make sure it is hand tight.

That's like I said back up the thread. My experience is also that it's best to use the right size/type of wrench to get the right leverage on it. If you use a regular flathead screwdriver you may not get it tight enough by feel. I use the gas nut wrench of my combo tool.

Owen
March 17, 2006, 04:38 PM
I'm using the combo tool to tighten the nut. Every two or threeclips, it isn't backing out, so I think I have the plug tight enough.

I am finding some soot on the outside of the gas cylinder, just behind the muzzle-end barrel band. Is that normal?

Edited for bad typing

30Cal
March 17, 2006, 05:24 PM
I am finding some soot on the outside of the gas cylinder, just behind the muzzle-end barrel band. Is that normal?
I've never seen an M1 that didn't do that. Yes. It's normal.

What did the gas piston mic out at? 0.5250" is the minimum (and it should obviously be round). 0.526" is the max, so there's a fine line between "new" and "toast."

Ty

Owen
June 6, 2006, 03:42 PM
I borrowed my ex-roomates Garand, and started swapping parts out.

After an hour, 40 rounds and a few burned fingers, I determined that the issue was definately the op-rod.

When I got home I remeasured the piston and came out with a diameter of .5246". I never would have guessed that .0004" out of tolerance would cause so many problems.

I looked for op-rod online for a while, and decided I didn't really want to pay the $150 for one. I called the CMP and spoke with John McClane, one of the gunsmiths at the Anniston, AL location. He told me to send my op-rod to him, with a letter explaining what was wrong with it.

About 2 weeks later I received a replacement. I finally got out to the range last night, and fired about 100 rounds without a malfunction.

Thanks for all the help folks.

Trebor
June 6, 2006, 06:36 PM
Glad you got your problems worked out. CMP does offer great customer service, don't they?

GoRon
June 6, 2006, 08:27 PM
Good thread.

Always can learn something new at THR.

Glad your gun is up and running!!

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