My neighbor came over Sunday with a brand new CZ 550 and a 20 MOA rail from US Optics. I am not familiar with these rifles at all, fact is this was the first time that I've got my hands on one. It has a dove tail action similar to a Sako. I need some input on mounting this rail. Is it necessary to have the action drilled and tapped for the mount screws? Can that rail move after it is mounted on the dovetail?