http://www.nicolausassociates.com/PD...ber%201942.pdf

Check out the specs in tha above captioned document.
See para 2a and 2.b.1.d.
The rifle in the pic is probably an early prototype and I'll bet the scope is a commercial Weaver 330C in one of their stamped side mounts. Shifting to the Redfield Jr would provide the flexibility needed to mount either the Weaver or a Lyman Alaskan whch was the other approved alternative.

Regards,

Jim