Leupold® mounts are every bit as rugged and dependable as the Leupold optics they’re intended to secure. With a huge variety of mounting systems, for nearly every type of firearm under the sun, you’re sure to find the perfect match for you firearm, and your style of shooting. This mounting system features larger through holes that accept the thicker 8-40 screw, and the standard 6-48 screw has been replaced by a shoulder screw to work with the larger opening. This will give 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. 8-40 screws are 41% stronger than standard 6-48 screws.
Sinclair, Issue:3B, Page:198