I know the Garand uses selected powders so as not to bend the op rod.
Is the M1A limited to much the same powders, or not?

What powder/bullet combinations have shooters had particularly good luck with?

I honestly don't know up front...how slow burn rate you can go...in competition, far, far better shooters than I didn't feel the need to wander very far from 4895, so I never saw the point in trying to prove the best riflemen in the game wrong. There was some interest in Varget when it appeared, but by that time fast twist AR's were starting to dominate. Dan Newberry's loads ,google them, pretty much set the accuracy standard I think.

IMR 4895 is the standard IMR 4064 is an excellent follow up. These are the only 2 powders I use in the Garand or the M1A.

Op rod on a m1a is a straight line. Garand is like a dogs hind leg they say. Op rod on M1a is one of the big upgrades from the Garand, along with the roller on the bolt.
Many people trash the non-GI op rods on the M1A in favor of the GI. Most prefer the TRW version. I don't know if this is really necessary.
Cleaning the carbon caking out of the gas cylinder is probably a bigger deal. They sell a drill bit on a screw driver handle for that. As it cakes up it changes the volume, and barrel harmonics. So the zero will shift.

Thanks, Terry - good to know.
I've got quite a little 4064 on hand, so that's what I'll use for now.

IMR 3031 was the powder used most in the match days of the M14 by the AMU 42 grs. 150 grain bullet 39 grs. with the sierra 168 intl. bthp

In the M1A I loaded 39 gr. IMR 3031 shooting the Sierra # 2200 168 gr. Int. Match BTHP using a LC military match brass.

That load was very accurate in a .308 heavy barrel bolt match rifle as well. I also used the same load in a .308 Rem 700 with the Hornady 165 gr. Spire Pt. for hunting.

That has always been an accurate load for me.

I'll try 3031, if II can dig some up.
Thanks.

Hodgdon has specific ".308 Winchester Service Rifle" data:

https://www.hodgdonreloading.com/reloading-data-center?rdc=true&type=54

Others may also.

Hornady does.

My M1a and my Garand love 4064 under a 168 SMK. I have owned several of both and for some reason, have never had one prefer 4895…never.

42grains and 47 grains of 4064 for my M1a and Garand respectively. Both were accurized by the USAMTU @ Ft Benning an hour and a half North of where I live. The iron sighted Garand shoots groups just a hair over an inch at 100 yds. The M1a is scoped and shoots ragged holes that a nickel easily covers. Both have taken a number of deer, the longest shot being 633 yds.

M1A's are made to handle both 7.62 military ammo and commercial .308 loads up to 180 gr. bullets. That's from the literature that comes with the rifle. They also state that loads like the Federal High Energy Loads are to be avoided.
The only powders I've used are H4895, TAC and IMR 4166. With 46 grs. of TAC and either the 130 gr. TTSX, the Sierra 125 PH, or the Speer 130 gr. HP, my Squad Scout puts four into one MOA time after time. My Socom 16 likes the 130 gr. Speer HP, and the 130 gr. TTSX. Four for 2 MOA for the Speer and about 2.4 MOA for the TTSX bullet. That's with a Leupold Scout Scope. E

Thanks for the info.
I've got quite a bit of experience with the 308, but this is my first experience with an M1A.
I'm glad to hear that my favored 165 weight range works well, and the 4895/4064 powder range works, also.

The M1 Garand and M-14 gas systems are different. The Garand's op rod is the gas piston and the M-14 gas cylinder has the piston in it separate from the op rod. The Garand's gas system works on a specific volume of gas to work.

OK?
Now I'm back in the dark - more research required, I guess.

M1 Garand op rod end. It is the piston.


M1a gas piston


M1a op rod end. The separate piston hits it.

Dave, it just seems that either system would require a "specific" amount of gas (volume) to work.

It's a combination of volume and pressure. There is some leeway, but you need "enough" gas at the "right" pressure.

I agree but the M1 gas system needs more volume and M2 ball ammo specs at 50K PSI. 7.62x51 150gr ammo specs at 60k PSI. The M1a/M14 has a short stroke gas system.

So, what range of powders do you consider suitable for the M1A?

4895 is the classic sweet spot, with 3031 on the faster side and 4064 on the slower.

Kinda what I was thinking - about like the Garand.
The 4350 will stay on the shelf.

Thanks, guys.