What's the difference?

USMC uses long, Army uses short, unless I have that mixed up, and or totally wrong... :uhh:

All I know is that Ukrainian immigrants are wankers :cool:
M24 is (and always has been) a "long" action. The decision to do this from the outset was based on a desire to have the option of upgrading select M24's from 7.62x51mm to .300 Win. Mag. at some future date. You simply can't stretch a "short" action.