To use these mounts require that your reciever be drilled and tapped, the hole spacing is as follows: 1st to 2nd hole=.400"; 2nd to 3rd hole =3.870"; 3rd to 4th hole = .400". It is recommended to find a qualified gunsmith to drill and tap your reciever and install the mount.
Our products are milled from solid bar stock with all work performed in our U.S.A. factory by American workers. While most manufacturers build a thinner rail that requires taller rings, we use a thicker dimension on our rails and lower ring heights that allow more room for porting the underside to eliminate shell ejection issues which provides a rigid platform for your scope to perform at its maximum ability. We also control the depth of the screw with a countersink and do not recommend Loctite to hold it in place. Each order includes T15 Torx head screws. Use 20 to 25 inch lbs. to install. If you have any issues we are here to help, use the "Contact Us" tab above and we will respond as quickly as possible.