Leupold Mark 4 8-40 Adaptable One-Piece Base for A-Bolt Short Action 20 MOA Matte Black

First mount that can accommodate both the 8-40 screw and a modified 6-48 shoulder screw. Larger through holes accept the thicker 8-40 screw while the standard 6-48 screw has been replaced by a shoulder screw to work with the larger opening. Gives you the flexibility to mount your rifle with the common 6-48 screw size or drill and tap your gun to accept the 8-40 screws. These bases will fit Winchester PBR, Remington Super Magnum, HS Precision and other 8-40 rifles without modification. (Some firearms will not work with these adaptable mounts. Check current offering for details.) 20 MOA.