Systematic Test: Garand Operating Modes

[Hick]

I've read posts from many on the ways an M1 Garand can be operated, and decided to do some systematic testing. I'm passing this on for anybody who might be interested.

My Garand is a 1954 vintage CMP Service Grade Special that does not have much wear. It has the standard gas plug.

My initial objective was to find minimum loads that allow me to operate the Garand three different ways: (1) as a single shot pull-- loads that fire accurately but do not even unlock the bolt-- letting me pull the bolt to eject and load the next cartridge (2) Using the SLED-- loads that eject and lock back the bolt, even if they do not properly cycle and (3) minimum load for full function.

For my first round of tests I used two bullets: 150 grain Hornady FMJ/BT and 110 grain FMJ round nose (actually, Armscor 30 Carbine bullets).

I used two powders: Hi Skor 700X for the lowest velocity loads, and IMR 4064 for the rest.

Results: Single Shot pull

10.0 grains 700X, 150 FMJ/BT, 1320 fps, nice single shot (loaded clip but had to manually pull bolt for each load)
10.0 grains 700X, 110 FMJ/RM, 1606 fps, nice single shot action

Eject and lock open with SLED

32.0 grains IMR 4064, 150 FMJ/BT, 1850 fps (I also tried to see if the action would cycle, since I reasoned that if the bolt would lock back it should cycle-- I was wrong, bolt would lock back with SLED, but short-cycled with a clip)

Full Function

Began to full cycle at 40 grains of IMR 4064 and 150 FMJ/BT, but I didn't get the most consistent velocities until 43 grains

43 grains IMR 4064, 150 FMJ/BT, 2409 fps
43 grains IMR 4064, 110 FMJ/RN, 2475 fps

YMMV, since a lot of this has to do with the tolerances in the gas cylinder and the op rod spring.

[Outpost75]

My experience with CMP rebuild with HM2-.312-160-5 bullet has been that 40 grains of IMR4064 cyclesreliably at 2200 fps and with 50-50 linotype-wheelweights gives accuracy equal toor better than HXP Ball M2 from the CMP at 20) yards.

[Hick]

Outpost 75-- It's amazing how close we are. Mine started to cycle at 40 grains 4064 also, and the mean velocity was 2196 fps, but with the 150 FMJ. I settled on 43 grains because I got the lowest standard error in my chrono data at 43.

[fastdadio]

Keep it coming guys. I'm taking notes. I have 4064 and some lee 170 fn/gc sitting on the bench and wondering where to start. I have my DCM Garand just beggin to get out of the safe after years of lockup.

[Adam Helmer]

After all my M2 Ball ammo was expended, I looked for a cast boolit that would function and group in my Garands. I never worked on loads that required manual cycling of the bolt. My cast boolits are old wheelweights and a dash of tin water quenched as they drop from the moulds and alox lubed gas checked projectiles. I tried Lyman's #31141, 311329and 311467 with mixed results. I finally tried the Lee C312-185-1R, a 185 grain RN projectile, sized .309", ahead of 36 grains of IMR4895, overall length 82MM.

The Lee boolit hits to the same point of impact as M2 Ball with the same sight setting as Ball required and function is 100%. I use this load for CMP matches locally where we only shoot 100 yards. I have no leading to speak of and the gas cylinder looks as fouled as was done by Ball ammo in the past. Hope this helps.

Adam

[DanOH]

Adam
Are you using a filler on top of that 4895?

[Adam Helmer]

DanOH,

No, I do not use any filler in my reloads now days. I used to use kapok until I read about ringed chambers and other pressure problems. That charge of IMR4895 fills the .30-06 case about 60-70%.

Hope this helps.

Adam

[DanOH]

Good to know...thanks