Marine Springfield Bases

[Kragrifle]

Late joining this discussion, but I always thought the 6 inch spacing was Winchester and the 7 1/2 inch spacing was for the longer Unertl scopes.

[Marine A5 Sniper Rifle]

Late joining this discussion, but I always thought the 6 inch spacing was Winchester and the 7 1/2 inch spacing was for the longer Unertl scopes.

The scope spacing had nothing to do with Winchester, or SA for that matter. Scopes had been around long before either got into the game. I suspect the 6" spacing originated due to ease on installation of the bases. The flat area of the FRSB was convenient, and one can only go so far down a 1903 barrel before wall thickness becomes a problem. The 7.2" spacing is common for externally adjusted scopes since it makes bullet impact movement calculations quite simple (1" at 100 yards is approximately 1 MOA with 7.2" spacing). This is an issue only because the A5 is an externally adjusted scope.

The real issue in this discussion is the difference between a Marine Mount (the part that holds the scope), and a Marine Base (the thingee attached to the rifle to which the Mount attaches). The Marine Mount is the highly modified #2 WRA scope mount with large dials and pointer you see on the WWI Marine A5 sniper scopes, which some seem to confuse with the Marine Base as shown in the 1928 WRA drawing shown in Brophy. The Marine Base is the set of bases required to mount a non-modified #2 WRA mount on a 1903 Springfield using 7.2" spacing. The Marine Mount uses Mann-Niedner tapered bases. Very simple, really.

Jim

[1903fan]

I'd go out on a yonder limb and wager that people often try to prove rifles they already have, and that is what influences the conclusions they come to.