One thing I've noticed.
My .223 load for my RRA NM A2 was very easy to come up with. Very accurate.
The M1A and Garand are more problematic.
Gerry
There is another factor when you throw in the AR word in the M1 and M1A discussion. In highpower shooting, ARs for the most part will let you commit some shooting sins and get away with a decent score. The M1s and M1As will blow you out of your position with your first shot if you do not have a solid postion.
The above statement holds true even shooting from the bench. You hold that M1 or M1A with varying shoulder pressure and grip, you can see the groups go all over the place.
Sorry for the side track there. Back to the original topic, 4064 is it.
Do your load development for your system, start at 41 and work up at .3 increment. watch for pressure. One of my M1As shot the best at 43, another at 42.3, and the another rifle at 44 (with Berger 168s and 185 Bergers) and the rest are all with SMKs.
The 42.3 load was convenient because that is the same charge I use with the 185 Bergers. And, the same load for my McCoy built M1.
Mostly for short range I just use 135 FB Berger bullets with 44 grains of 4064.
The loads are in my rifles, yours may vary.