ORIGINAL: MISwampDog
It was just brought to my attention that it's two different rounds.
Whoever "brought it to your attention" doesn't know the famous shoe polish from the other noted substance!!
There is BUT ONE .30 caliber, Model of 1906 U.S. Government cartridge. It is the one that was designed at Springfield Armory, first used in the Model 1903 Springfiled rifle, and adopted in the year1906. Between 1903 and 1906, the rifle was made to shoot the .30 cal., Model 1903 cartridge, which is essenttially the same, except the 1903 had a longer neck so it would better handle the 220-grain roundnose bullets in use then.
Yes, there are many thousands of different loadings, but the CARTRIDGE CASE remains the same one for ALL .30/'06 ammo......
ANY rifle in good condition and designed and chambered for the .30/'06 will safely shoot almost any brand of FACTORY LOADED.30/'06 ammo. I said "almost any" because, no doubt, there are exceptions lurking somewhere!