EDIT:Thought you were talkin' bout the service rifle.
The cartridge itself offers similar ballistic performance in most firearms to the .30-06 Springfield that it replaced in U.S. service. Though shorter, standard loadings fire similar bullet weights at similar velocities. Modern propellants allowed the same velocity from a case with less capacity. The smaller case requires less brass and yields a shorter cartridge. This shorter cartridge allows a reduction in the size of the firearms that chamber it.
Edit: (in John Madden's voice) So here's a guy who's replying to a reply that's not there anymore, and that's kinda like a double negative, but opposite. Heh, heh.