You have to underload .3006 for Garands, right? The modern hot ammo tears ‘em up?
It depends on the powder burn rate...they were really designed around IMR 4895 powder or its equivalent. There is modern ammo available specifically targeted to M1s (essentially recreating the old M2 ball), and a ported gas plug is available that will take the risk out of “uncertain” ammo.
Well, I can't say I'm an expert on reloading for the M1, Laz, 'cause I'm not. But I had a friend who worked out a good load for himself over the years, and he gave me his specs:
o Lake City brass trimmed to 2.484 in. case length, primer pocket fully reamed out
o Sierra 150 gr. jacketed pointed soft point bullet
o 47.5 gr IMR 4350
o 3.185 in. O/A
I never saw a reason to change this for target shooting. However, I did look up the powder loading for this bullet, in the Lyman 47th Reloading Handbook, and their suggested starting load was 49.0 gr of IMR 4350, with a max loading of 57.0 grains. I never increased the load, but it looks like the powder my friend suggested was a light load. If a heavier load for the Garand was desired I'd start looking for bulged primers, or stretch marks on reused brass.
Then I looked at the IMR Handloader's Guide, and for the above type 150 gr bullet they had 59.0 gr (!) of IMR 4350.
I don't know what else to say. Maybe you have some advice or experience on this?