M1A inconsistent1

[Kingcreek]

I’m stumped and I have 40 years experience and thousands of rounds of history with M1a rifles.
1000 rounds is nothing to that rifle. Nothing would deteriorate in 1000 rounds that would cause that. Not the gas piston tolerances. Hope you find it and report back. I’m curious.
I would ditch the bipod first and go to bags as a shooter that likes to try the cheap fixes first.

 

[Megawatt maker]

I’m stumped and I have 40 years experience and thousands of rounds of history with M1a rifles.
1000 rounds is nothing to that rifle. Nothing would deteriorate in 1000 rounds that would cause that. Not the gas piston tolerances. Hope you find it and report back. I’m curious.
I would ditch the bipod first and go to bags as a shooter that likes to try the cheap fixes first.

Hence why I posted it. I'm stumped too. I can't see the play between the front band and gas block causing it, but its the only thing I've found that's different. Before this, the gas lock stopped, without any excess force, right at the point where the gas plug would thread in. Now, the lock turns about an extra 20 degrees or so until it tightens. The difference in .022 mm, as per my feeler gage (can't see to locate my SAE gages).

I'd be surprised if that's it, but can't find anything else, despite those who seem to think I've somehow forgotten how to shoot all the sudden.

I'll post result when the shims come. It will either fix it...or not.

 

[marksman13]

Hence why I posted it. I'm stumped too. I can't see the play between the front band and gas block causing it, but its the only thing I've found that's different. Before this, the gas lock stopped, without any excess force, right at the point where the gas plug would thread in. Now, the lock turns about an extra 20 degrees or so until it tightens. The difference in .022 mm, as per my feeler gage (can't see to locate my SAE gages).

I'd be surprised if that's it, but can't find anything else, despite those who seem to think I've somehow forgotten how to shoot all the sudden.

I'll post result when the shims come. It will either fix it...or not.

Nobody is saying you forgot how to shoot. But, your issue looks like a shooter problem and not a hardware problem. I’ve seen it happen. There’s nothing mechanically that causes a rifle to shoot sub-MOA and half MOA in your case and then blow up to patterns rather than groups at 200 yards. The difference is you changed the load distribution on the bipod and elevated the front of the rifle. I’ve seen it happen to good shooters. You change position to shoot uphill or downhill and that changes the way your face interfaces with the stock and allows parallax to play hell with your eyes. It also changes the way recoil affects your rifle. Recoil that was straight back into the shoulder with the bipod loaded is now allowed to move slightly upward and potentially side to side. We can debate all day if recoil movement actually affects the bullet or not, but I’ve seen poor recoil management effect group size.

Most of the time, when a shooter says “I’m 100% sure it’s not me.”, it’s the shooter.

 

[Ignition Override]

I’m somewhat an untrained shooter.

Any instruction has been totally random and sporadic.

This first M1A (S.A. Standard) was acquired several weeks ago, it has been fun.

Were I to suddenly die or become incapacitated next week (for example), —-no regrets—- about simply owning it with some plinking.

 

[nettlle]

I’m somewhat an untrained shooter.

Any instruction has been totally random and sporadic.

This first M1A (S.A. Standard) was acquired several weeks ago, it has been fun.

Were I to suddenly die or become incapacitated next week (for example), —-no regrets—- about simply owning it with some plinking.

M1A's are very enjoyable to shoot. I've had mine a bout a year now.

 

[Megawatt maker]

Problem solved.

The shims did the trick. In fact, it shoots even better than before. Sub MOA all the way to 300 yards.

Waiting for a nice wind free day to really put it to the test out to 600. I'll post tesults

 

[Charlie98]

The shims are magical or something. There's a lot going on down there at the M1a gas lock, if it's not wired up straight, you will have problems. Aside from an obvious mechanical issue, that's the first place to go.

 

[arsterling180]

The m1 garand and m1a both require some science and voodoo black magic to get very accurate.

 

[Megawatt maker]

The m1 garand and m1a both require some science and voodoo black magic to get very accurate.

Science, sure, but not black magic.

I think my next move should be to unitize the gas block/front band.

I've read it can be screwed (drill and tap a small hole), weld it, or as a quick and dirty...JB Weld it...or other kind of epoxy.

 

[nettlle]

Good thread. Thank you for posting. Did some research on shimming the gas block and the next time I clean my M1A I'm going to check if it needs shim(s).