Garand short cycling problem--please help.

[BamBam-31]

Finally got a hold of my buddy's Garand, which had been short cycling for months. Opened her up, and discovered two things:

1. Op rod is bent. It's supposed to be straight, right? Judging from the wear marks, it's rubbing up against the handguard. When I remove the spring, however, the op rod and bolt do slide back and forth rather freely when the rifle's tilted. How does one fix a bent op rod? Hammer and anvil, call Gimli, or just order another one?

2. Gas cylinder lock is loose. In order for the gas cylinder and handguard to fit snuggly, the lock has to be turned almost 200 degrees past where it needs to be for the plug to go in, whereupon it stops. So you have to back it up to line up the plug, and when the plug goes in, it pulls the cylinder forward, and the handguard ends up being loose. Does this misalign the cylinder to the gas port? Maybe a shim is in order?

I don't have the gauges necessary to check op rod and gas cylinder, but maybe those are worn as well. Prolly no fix for that other than buying replacment parts, right?

Any other suggestions?

 

[4v50 Gary]

Op rod is bent at two places on the M-1 Garand. It's designed that way.

The gas cylinder is suppose to be snugged down tight. Who cares what direction the plug is, just so long as it's tight and the cylinder doesn't rattle. Rattle = vibration = inconsistent harmonics = inaccuracy.

 

[BamBam-31]

Okay, so bent op rod = normal. Gotcha.

Gas cylinder is NOT snug. Accuracy is not even a concern right now, the rifle's not cycling. We'll get to accuracy after the rifle cycles properly. Would the loose gas cylinder be to blame for the short cycling? It's not the direction of the plug, but the cylinder lock (is this the right term?) that concerns me. Basically, in order for it to be lined up for the plug, it needs to be loosened more than half a turn.

Somehow, I think the rifle needs more than just a shim.

 

[Trebor]

The first rule of gunsmithing is try the easy fixes first.

In this case, buy a NEW Op-rod spring from a vendor such as Wolf Springs (standard weight spring ONLY) or Fulton Armory. Don't get a spring from the CMP because you want a new spring for this and the CMP springs are take-offs from unservicable rifles and might not be any newer then the spring in your buddies rifle.

Install the new spring, lube the rifle with appropriate grease (not oil), tighten down that gas cylinder a bit and test fire.

The odds are good that installing a new spring, just by itself, will fix the short stroking problem. I found this out first hand by asking some old time GI smith's how to fix a short stroking problem in a friends rifle and it worked.

When you get the new spring, lay it out side-by-side against the old spring. Odds are that the new spring will be noticeably longer then the old spring that has been compressed for all these years.

If installing a new spring doesn't work, there are other things to try, but the troubleshooting gets more difficult. Try this first and report back.

 

[stans]

Two things, what ammo is causing the short cycle and does it short cycle with other ammo?

How is the condition of the gas port? Clean or fouled? Correct or oversized?

 

[Onmilo]

The rifle has been lubricated with grease,,,,right??
Take it to a gunsmith familiar with M1 rifles.
There are too many things that can cause short cycle in an M1 to try and diagnose it on the internet.

 

[30Cal]

Most rack grade garands have some play in the gas cylinder. It's pretty much the norm and doesn't often adversly affect the function of the rifle. However, if there is a lot of fouling (some fouling is expected) visible on the barrel with the gas cylinder installed, that might indicate a problem.

The oprod tube should appear straight when viewed from above. If it passes the gravity check, fit shouldn't be a problem from a functional standpoint. Go ahead and check that the follower rod (attached to the spring) isn't contacting the bullet guide when the action is cycled.

I agree that you should start with the oprod spring. Another thing to check is the dia of the oprod piston. 0.525" is the minimum. If it's under, get a new oprod (a lot of oprods sold as new are really refurbished, so ask before you buy). Also, check that the follower rod (attached to the spring) isn't contacting the bullet guide when the action is cycled.

The gas cylinder is not something you're going to be able to check--it's got it's own unique gage. I'd worry about that last.

 

[BamBam-31]

Don't understand how a new op rod spring would help the short cycling. Wouldn't a stiffer spring make it more difficult for it to cycle?

The ammo was LC surplus. That's all that was fired through it so far.

The rifle's been greased by me with Brownell's action lube. Gas port has also finally been cleaned out by me, but I don't know how to check if it's correct or oversized. Didn't notice an unusual amount of fouling on the exterior of the gas cylinder, either.

The follower rod does seem to contact the bullet guide when cycled. Actually, the bullet guide looks pretty darn new compared to the rest of the rifle. Replacement part?

I'm gonna measure the op rod with my calipers and report back later.

Thanks for the suggestions. Very helpful.

 

[BamBam-31]

Op rod tip measured in at a hair under .530", maybe .529". Any more suggestions?

 

[mparris71]

From the "War Department Technical Manual TM9-1275" Page 95
Short Recoil possible causes
Undersized Piston, oversized Gas cylinder, undersized barrel at splined section, Carbon or foreign matter in gas part of barrel, carbon in gas cylinder, O.P. Rod Binding, Vavle Leak in gas cylinder lock screw, Defective O.P. rod spring, Bolt Binding, Burs foreign matter, Improper Lubrication, Rusty or ringed Chamber.
The Piston on the OP Rod should measure "0.525 or more" to be considered "servicable"

 

[dfariswheel]

Some possibilities.

Is the rifle ACTUALLY short recoiling, or is the case failing to eject.
Check the extractor, ejector and their springs for damage, wear, weak springs, or fouling.
Sometimes what LOOKS like a short stroke is actually a failure to eject.

Gas leak? Check the gas cylinder and barrel area for soot or exposed fouling indicating gas leaking out.

Tight gas cylinder lock screw? Check the valve in the lock screw. A weak spring or grit under the valve may be holding it slightly open, leaking gas.

Chamber problems? CLEAN it with the GI chamber cleaning brush.
(Be sure the brush is good. Often people wrap patches around the brush to wipe the chamber, and this ruins the brush).
Inspect the chamber with a mirror. Look for pitting, rings, chamber reamer chatter marks, etc.

Since the bolt and op rod pass the "tilt test" and move freely without the spring, UNLESS the stock is binding on the rod, it's likely OK.

Check the gas cylinder inside for any signs of excessive bore wear, or "Bubba" alterations or damage.

Unless the gas cylinder is obviously leaking gas around the barrel, being slightly loose should not cause problems.

Your gas cylinder lock turning 200 degrees is no problem. GI locks are simply turned down to stop, then backed up to allow insertion of the lock screw. As long as the lock needs to be turned LESS than one full turn, it's OK.

With the lock in place, the op rod locked back, and the lock screw out, pull the gas cylinder forward against the lock.
Look inside to see if the gas port into the barrel, is more or less centered in the gas cylinder cut.
Allow the bolt to close and check to see if the head of the op rod is just behind the gas port.

Check the gas cylinder lock, and the front face of the gas cylinder for any gaps when the screw is snugged down. A warped or altered cylinder or lock will leak, and there will be signs of leakage in the form of soot.

Replace the op rod spring with a certified NEW spring. Yes, I know this SHOULDN'T allow short stroking, but a bad spring causes all kinds of odd problems in the Garand.

 

[BamBam-31]

Great post, dfariswheel. My buddy finally decided to drop off the rifle at our local smith's. Dunno how knowledgeable he is about the Garand, though. He's a very good pistolsmith, but battle rifles are usually given over to a friend of the shop.

When we get it back, I'll check for the things you mentioned. Thanks a bunch.