That dosnt appear to be the Kollmorgen scope. The elev & windage knobs on the Kollmorgen were toward the front of the scope, should fit just behind the front ring.
That is the same G & H mount used on the Marine Sniper M1s.
There should be a date stamp on the barrel, the USMC used barrels stamped 1951,52 & 52.
The G&H mount was sold as surplus and several were mounted on M1s.
The flash hider may have been removed, they didnt really work well.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071