I just HAD to get this info over here from the archives... indulge me.
I've posted this here before, so if some guys are sick of reading it, I apologize to them. My cast load for the M1 was developed when I was a poverty-stricken undergraduate student in the 60's. Bullet was 311284, cast out of wheel weights (which were much harder in 1968 than they are today); Hornady gas checks, the then new-fangled Alox-Beeswax lube; and they were sized to .309 for my rifle. Powder charge was 42 grains of WW II surplus 4831 that was sold by Hodgdon for $1 a pound; less if you bought it in bulk. Over the charge was 1/4 sheet of TP; old FA or WW II contract ball cases; CCI 200 primer. The bullets needed to be seated deep ( to the "dirt groove) in order to fit in the magazine. There are a few "rules" violated here: powder allegedly too slow for M1 gas system, bullet too heavy; bullet seated deeply into powder space. The charge is so light that the op rod seems to get a long gentle shove instead of a sharp push. I never had any difficulties with it. Like wise, the deep seated bullets did not seem to seriously hurt grouping. Groups (fired prone) went about 2-1/2-3" at 100 yards, about the same as the M2 ball that was around then. (this was not a "match" rifle) I may have had one or two failures to feed in the hundreds of rounds that I fired. I used to break it down and clean after shooting this load; and I would usually find a few flecks of lead on the gas piston that would brush off with an old bronze bore brush: I cleaned the gas cylinder with a 16ga shotgun brush and patches, and never had a lead problem there.
Today I would start with 40 grains of new-production 4831; if you are using post-1970 wheel weights, you will probably need to add some type metal to it. One thing you must never due with the M1: never, ever load the bullet to engrave in the throat. You will be asking for a slam-fire and the results won't be pretty.
BTW, the same load tweaked for the 03A3, and shot at 200 and 300 yards, got me my first Master classification in 1973.
Resp'y,
Bob S.