Owen
Moderator Emeritus
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?
Any suggestions?
M1 Rifle short stroking
- Thread starter Owen
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dfariswheel
Member
- Joined
- Dec 26, 2002
- Messages
- 6,656
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.
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.
mustanger98
Member
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
Member
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
Member
Chris Orndorff said:
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
Member
- Joined
- Dec 26, 2002
- Messages
- 6,656
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.
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
Member
dfariswheel said:
I'm not doubting anyone, just trying to understand. Does the same hold true for the M-14/M1A?
mustanger98
Member
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
Moderator Emeritus
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?
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
Moderator Emeritus
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.
Now, It short strokes after the first four or five rounds.
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?
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
Member
http://www.fulton-armory.com/ShortStroking.htm
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.
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
Moderator Emeritus
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.
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
Member
Take a careful look at the face of your gas plug. They have been known to crack from time to time.
Ty
Ty
loadedround
Member
Mamy times your gas cylinder plug loosens up and backs out causing short stroking. Make sure it is hand tight.
mustanger98
Member
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
Moderator Emeritus
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
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
Member
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
Moderator Emeritus
Finally
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.
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.
GoRon
Member
Good thread.
Always can learn something new at THR.
Glad your gun is up and running!!
Always can learn something new at THR.
Glad your gun is up and running!!
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