Bgvmt, it is a Weaver 82 base with PRW low rings. I had to cut a new cross slot just in front of, and slightly overlapping the forward most mounting screw hole so that it would accept the forward position of the rear ring, and I am not terribly happy with the fact that the scope mounts in front of any vertical support, but it seems relatively rigid and shoots right at MOA. I do plan to install a block in the rear sight dovetail, machine it to mate to the bottom of the base, tap it and secure the base there for additional support and piece of mind.