I don't think any specific cartridge matters now. The rifle would have used the M1icon ammo originally and then still used the M2 after it was adopted...is there going to be a big difference? If you look in the back of Cartridges of the World, in the back...it has a whole section on military ammo and what powders are used. .30 uses 4895IMR for one of the loadings and you should be able to work with that...