Looks an awful lot like a Redfield Junior to me. John Redfield, according to what I'm told, was an American sniper in the Great War who thought that the job could be done better, so, when he came home, he darned well DID it better.
Wonderful mounts: you can remove the scope and put it back on without changing zero. They are necessary if you should have one of those wonderful old, darned-near-indestructible Bausch & Lomb Balvar turretless scopes. ONLY problem is that you have to use the proper Redfield rings with them. They are incredibly solid and don't cost much more than regular Weavers.
To remove the scope, you remove the nut at the right-hand side of the back end of the mount, pull your scope 90 degrees sideways and lift it off. Reassemble in reverse. SUPER solid. They were used on a fairly large number of sniping rifles during the Second War. They have been around for a long time and there's still nothing to beat them.
If I were building a sniping rifle, I would start with a Mark III Ross action and a Redfield mount.
Stith also made a LE mount that was similar.