The Gibbs replica scope is a copy of the Weaver 330C or M73B1. The M73 was actually the militarized version of the Lyman Alaskan. It was planned for use on the M1903A4 but due to prodction difficulties none were delivered in time for A4 production. Some became available in time for issue with the M1-C in 1945.
M73B1 WAS the code of the military Weaver 330C
The Lyman Alaskan scopes were given the codes M81 & M82 - depending on the reticle style of that particular model scope.
I make covers for all the above, plus a few more besides!!