Reduced powder charge for M1A

Denny Gibson

Mar 5, 2017
Chillicothe Illinois
I just purchased an loaded M1A. I'm getting old and would like to work up some rounds for reduced recoil. I'm using H4895 and have, with this powder, used the "60% rule" to come up with mild shooting but accurate rounds for bolt action rifles. On the M1A (Sierra Bullets manual) the top load for H4895 is 39.9 grains ... 60% would put the low recoil round in the 24 grain region. The question is how low can I go before the action fails to cycle reliably. Anyone got some thoughts on this? Please share any reduced recoil loads you have had success with on an M1A.

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You will need to drop the charge till it won't pick up the next round. Then add back for dependable functioning. 60% won't apply to your autoloader.

Retirement is staring at me and I " feel " for you.
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What you are going to learn is this:

At some point, as you reduce your loads, THE NECK WILL STOP SEALING.

When that happens it will blow all sorts of chamber shmootz past the cartridge case, and back into your face. Violently.
I promise you won't like it.
Remember you are dealing with an open-breech design. Nothing to contain that shmootz when the case neck doesn't seal.

I learned that my 30-06 Garand stopped cycling with Varget when i dropped the charge down to about 38 grains. A couple grains less, and was getting blasted in the face with chamber shmootz.

Also, as you reduce loads significantly, be aware of the amount of drag on the bolt caused by the stack of ammo in the magazine. You will find a load that might eject OK if there is no ammo in the magazine. But it will fail if the magazine has any rounds in it.

What do you need the gun to do?

I'm predict you can reduce your normal M1A load by 20%, at which point it will stop cycling reliably with a loaded magazine. At 30% reduction, you will experience unpleasant blow-by of shmootz.
I never assembled a reduced load for a semi-auto rifle. I know that reduced loads using 2400 can be shot with a bolt rifle and springs can be changed out for semi-auto handguns. Are there lighter springs for M1As so they can shoot reduced loads?
In the way answering what I want the rifle to do:

I shoot this gun in a match called the “Mauser Match.” All the rifles are old, military weapons. If I shoot all 4 relays it consumes 80 rounds. I can’t shoot 80 rounds with any of these rifles without more battering than I want so I load them down to a sustainable recoil. All of my bolt guns are loaded this way but I haven’t worked out anything for the M1A or Garand. Being gas guns they are easier on the shoulder but, at 75, I could use a break there, too.
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The faster of powder you use the less charge it takes to get the peak pressure to seal the case neck, and that same event seems to help opteration. Obviously there is a limit...
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Bjung ... not that I know of.

James ... thanks! Another dumb question: Does the M80 generate less recoil?
Felt recoil is highly subjective. I would think that the military round would be no pussycat. If you can add weight to the rifle that would help, along with lighter bullets. Physics has some pretty strict laws.
Schuster adjustable gas plug.
They make them for both the M1 Garand and the M1A.
That's sounds awesome. But how does that make the hole in the barrel bigger for more gas to function at lower psi.
Is the issue not that it is overgassed?
The OP is trying to reduce felt recoil.
If you use reduced loads you need more volume to the piston. He asked about reduced loads. Maybe it's moved on from there so I'm in the past.