Weaver Rail Mount

A Weaver rail mount (Picatinny type) is a system to connect telescopic sights and other accessories to rifles, shotguns, pistols, archery bows, etc. which uses a pair of parallel rails and several slots perpendicular to these rails. The slots on a Weaver system are primarily used as a clearance of the locking screw that tightens the clamp to the rail. The slots in a Picatinny system serves as clearance for locking screws as well as a lock-bar to hold accessories in place and dramatically reduce recoil effects on scope alignment. Some Weaver-type accessories have a bar that fits inside the machined slots on the rails while many others do not. A Picatinny system consistently uses a locking bar. Older Weaver systems used two pieces mounted a distance apart from one another typically on the receiver of a rifle over the bolt opening where the bullet would be inserted and/or ejected. With a one piece rail, the system eliminates alignment problems of the two piece system than can put undue stress on a rifle scope and also eliminates alignment problems between the scope and rifle barrel parallels and bullet Point Of Impact (POI). Also the two piece system must be mounted to exacting tolerances to one another to ensure perfect alignment using a scope alignment device called Alignment Sleeves, while the one piece rail system remains consistent in alignment. The two piece type can be problematic when some rifles will not allow for the two pieces to be mounted due to metal thickness of the receiver or other issues of receiver length that will not allow for proper distance to hold the scope. In such cases a single mount is used and a smaller scope is mounted.