Just picked up an M1A with a Douglas barrel and according to the seller it has 1600 rounds through it.

Which bullet and powder combinations worked well for your rifle? This will only be used for target shooting

There is an old thread near the end of the reloading forum with just this information.

Start at the last page and work forward.

Old school - 168 Sierra with IMR 4895 or 4064.

New school - 135 Sierra @ 200 & 155 Sierra Palma bullets at 300 & 600 with any of the medium burn rate powders.

B

The rifle included 8lbs of H4895

H4895 is excellent.

Somewhere around 43.5 grains with a 155 grain bullet or possibly around 41.5 grains with a 168 grain bullet.

This with traditional hollow point match bullets, possibly not with the slightly longer plastic tipped bullets, but maybe not far off.

Sierra has at least two 155 grain Match King hollow point bullets.

One is the more aerodynamic, "Palma" bullet.

It is for long barrels with slow rifling.

The older regular 155 grain Match King hollow point is better suited for an M1A.

Several companies make their 168 hollow points to be very similar to each other.

That stuff is unobtanium and quite a good powder for ARs @ 600 for maximum velocity and accuracy. I'd save that for an AR and find somthing else for that ancient po-go stick.

B

41.5 IMR 4895 behind a 168 gr HPBT is a common match load. It is all I use in my 308 M1 and AR10.

This

This is the original Sierra Palma 155 grain bullet.

https://www.sierrabullets.com/product/30-caliber-7-62mm-155-gr-hpbt-matchking/

Note the part number, 2155 (not 2156).

It is not as severally aerodynamic as the later Sierra Palma bullet, part number 2156, here.

https://www.sierrabullets.com/product/30-caliber-7-62mm-155-gr-hpbt-palma-matchking/

The older 2155 is better suited for semi-auto rifles and regular rifling twist rates.

The newer, 2156 bullet is designed for much slower, 1 turn in 14 inch rifling, used in long barreled, bolt action Palma rifles.

The older 2155, just happens to be legal for Palma shooting and was Sierra first effort for that.

It works great in M1A rifles.

The more aero 2156 bullet is more sensitive to defects, loose or long throat chambers and is affected by imperfections more easily in faster rifling.

Also it seats deeper into the 308 case to fit the M1A magazine, due to its longer, aero shape.

I have an M1A with a medium weight Douglas barrel. I use the classic "Camp Perry" load, 168 gr SMK or Nosler 168 gr Custom Competition with 42.0 grains of AA 2520. I have tried 175 gr bullets and while accuracy was really good, I only have 120 yards to work with at the moment.

I like 2520, I've used it for 223 in high power.  Meters great

Google Nosler Pro Shooters Shop...they have blem's at great prices....that will serve you well.
Always be mindful of 2520...temp sensitive

168 or 175 grain match bullets will give you the best results.

Brass selection will determine powder charges.

I use 40.0 grains of IMR-4895 with 168's in Lake City brass. 40.5 grains is considered a maximum load in Lake City brass.

40.7 grains of IMR-4064 also works well for me in Lake City brass with 168's.

41.5 grains of IMR-4895 is a good load in commercial brass with 168's.

H4895 needs to be downloaded .5 to 1 full grain lower than the IMR-4895 option.

It's been a favorite of mine for a few decades and I use it for almost everything, .223, .308, 30/06, 8mm, 7.62x54r, .303 and I'm sure a few others I can't think of at the moment. Shooters World Match powder shot exactly the same for me with the same powder load in .223, so much so that I honestly think it IS the same powder.

You can make several powders work if you have trouble finding powder.   For example, there is an old match load available with IMR 3130 powder and 168 HPBT bullets, (which I don't recommend unless that is all you can get).  Ball C-2 can work, as can W748.     But as you can tell you don't have to work too hard to get IMR 4895 or H4895 to work with the appropriate bullets, if you can find those powders.  Powder burn rate matters for the op rod, you have to be in the right range for the gas system (but I don't think it's as sensitive as the Garand system).

http://www.m14.ca/reloading/14_loading.pdf

https://www.ssusa.org/content/longtime-ssusa-author-glen-zediker-passes-away/

Winchester commercial case + 42.0 gr IMR-4064 and any Sierra bullet you'd like.

I'd start with the 175 SMK.

Depending on twist rate 168 Sierra's HPBT, IMR-4064, CCI-200, LC Match brass works great-
Bergers 155-175 works great in the Krieger Barreled M1A's the 175's the best, twist rate 1/10
and 1/11 heavy contour. Even the old pull the Match LC bullet replace with Sierra 168 HPBT
(aka.. Mexican Match) in the Supermatch M1A's shoots good.

-Garland

My standard M1A load is a 175gr SMK w/ 41gr of 4064.  Gets them to 2625fps out of a NM barrel.  This is my attempt to replicate the Mk 316 Mod 0 round.  I probably don't need 175gr bullets since I rarely shoot past 600yds, but I can get them cheaper than the 168gr SMKs.  My typical shooting is between 300-600.