Older Russian battle-rifle caliber, used in many Eastern European and Soviet weapons, Dragunov, M-44, M91, M39, etc.
Since .308 is similar to 7.62x51, I would put 7.62x54R between .308 and .30-06 in terms of ballistics.
The M44 (20" barrel, bolt action carbine) is _loud_ and cheap to shoot with surplus 7.63x54R.