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Posted: 12/1/2012 11:19:29 AM EDT
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I've got a SA M1 Garand that was built on 42 and rebuilt in 45. Granddad picked it up at a gun show in California many many many moons ago.
Went to the range to try it out with some American Eagle M1 Garand ammo. Getting a failure to fully extract each round. The bolt partially travels to the rear with the brass but not far enough to eject. I've cleaned the rifle from front to back, very detailed and really took my time getting old carbon out. Any ideas? I'm considering sending it off to Fulton Armory to have it serviced but if I can get this baby running I could use that money for more ammo. Thanks in advance for any help. |
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It isn't getting enough gas to the piston. There are several things that could cause this. The most common being a loose gas plug. The second most common being the gas valve in the gas plug being partially open. Third most common is a misaligned gas cylinder that is partially obstructing the gas port. Next would be a gas port that is partially or fully closed by corrosion. It is also possible that the operating rod is bent or the stock may need to be relieved. To check for this, remove the action from the stock. Remove the recoil spring from the operating rod.. Hold the rifle horizontally by the back of the receiver and the gas cylinder. With the bolt fully in battery, tilt the rear of the rifle down about 45 degrees. The bolt should open fully to the rear by force of gravity. If it does, put the action back in the stock minus the spring. Try the tilt test again. If the bolt does not open like before, then the stock is rubbing the op rod somewhere and preventing it form working properly during firing. |
| also try different ammo mine like my reloads and shoot great with them rember to shoot ammo for m1 grands and check the op rod like the previous post said to and then and your spring for it i have had to replace the springs in the operation rod they wear out and fixed the problem |
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Well thanks for the reply guys, took it apart, did the tilt test and it looks like the op rod is bent.
And of course looking around the op rod is hard to come by, some rods appear to be made for 1950's Garand, so does that mean it won't in the 1940's model? I also found this Columbus Machine Works who claims they can repair bent op rods...anyone know them? http://www.columbusmachine.com/oprod.htm Suggestions so I can get this heirloom running again? |
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Quoted: And of course looking around the op rod is hard to come by, some rods appear to be made for 1950's Garand, so does that mean it won't in the 1940's model? Except for the very first op rods made in 1937/38 for the "gas trap" M1s, all other op rods are functionally identical. Don't get caught up in that "collector" stupidity. So long as the op rod is a USGI issue piece, it will work and fit properly regardless of when it was made or by whom. |
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OK--you should know that op-rods aren't straight (not perfectly straight) to begin with--so presumably the op-rod is dragging noticeably and binding in the op-rod channel, yes?
And you HAVE unscrewed the gas plug and lock and confirmed that the port is centered in the gas cylinder window? Columbus Machine is good to go--although you might also pick up a good, serviceble op rod for $100 at the seller forums at CMP or Jouster with a little looking. CMP... Jouster... Good luck. |
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Checked the screw and piston and both seamed ok but of course I'm no expert. Centered the piston to the window as best I could. I would like to get the rod repaired, it's the safe queen and handed down within the family. I figure that if you have guns they better go bang or whats the reason for having them.
This is what I'm looking at: Wear in the channel 
Op rod is upside down but has wear which matches the previous pic 
Tried to get a overall pic 
The rod appears to a slightly pulling to the right about 4 to 5 inches at the end. It also raises some and drops back down about the same point 
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OK, I'd say sending the op rod off to get reworked would be worthwhile--having an op rod which runs true will absolutely have an accurizing benefit besides.
There are no pics of the gas cylinder itself. How worn does the finish look--is it black, grey, or slver? Last item--maybe make one more range trip to test the integrity of the gas system before you send the op rod off. Put a piece of scotch tape on/across the top of the poppet valve, and see if it blows off when you shoot. If it does, the gas poppet valve itself might be leaking gas, and that could easily cause your short stroke. You can try cleaning it--soak it in Hoppes for awhile, then press the valve down onto a punch to compress the spring and expose the valve, and try to clean the seating shoulder of the valve as best you can. Here is a pic of the valve spring fully compressed PIC... just to give you an idea what you are trying to accomplish by pressing the gas plug down onto a punch. Good luck. |
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Well I checked the gas poppet and looked ok, the gas cylinder it a bit newer so its got a darker tint, replaced in the rebuild from what I understand.
The pics 
The springs should be the from the rebuild as well, the rifle was purchased back in the 80s and "sat" in a sofa bed for 20 years. |
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You didn't state whether it passed the tilt test. If so, leave the oprod alone. I don't see any wear marks there that are worth fussing over--pretty typical. Your gas plug should look like this.  Yours appears to be stuck open. Replace the gas plug. Also, the gas cyl and plug are stainless, so even on rifles with "matching parts", the gas system often doesn't match. The shiny gas cyl was a big complaint in it's early days of WWII. The oprod piston should mic at .5250" minimum. |
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Quoted:
You didn't state whether it passed the tilt test. If so, leave the oprod alone. I don't see any wear marks there that are worth fussing over--pretty typical. Your gas plug should look like this. Yours appears to be stuck open. Replace the gas plug. Also, the gas cyl and plug are stainless, so even on rifles with "matching parts", the gas system often doesn't match. The shiny gas cyl was a big complaint in it's early days of WWII. The oprod piston should mic at .5250" minimum. No the rifle did not pass the tilt test, the bolt ran fine but once I installed the op rod it wouldn't move on its own. I'm holding the plug open, was checking if the spring worked. Its normally closed. |
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Quoted: Quoted: You didn't state whether it passed the tilt test. If so, leave the oprod alone. I don't see any wear marks there that are worth fussing over--pretty typical. Your gas plug should look like this. Yours appears to be stuck open. Replace the gas plug. Also, the gas cyl and plug are stainless, so even on rifles with "matching parts", the gas system often doesn't match. The shiny gas cyl was a big complaint in it's early days of WWII. The oprod piston should mic at .5250" minimum. No the rifle did not pass the tilt test, the bolt ran fine but once I installed the op rod it wouldn't move on its own. I'm holding the plug open, was checking if the spring worked. Its normally closed. OPROD repair usually means they'll replace the piston and perhaps rebuild the lug at the back end. In your case, you'd still need to have someone fit it to the rifle. It may be cheaper to find a new rod (although they aren't guaranteed to drop in). Check the face of the gas plug for cracks. |
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