Nikko Stirling 1PC ALLOY WEAVER BASE HOWA S-ACT
The Picatinny locking slot width is 0.206 in (5.23 mm). The spacing of slot centers is 0.394 in (10.01 mm) and the slot depth is 0.118 in (3.00 mm).
The only differences between the Picatinny rail and the similar Weaver rail are the size of these slots and the fact that they are standardized. Weaver rails have a slot width of 0.180 in (4.57 mm), but are not necessarily consistent in the spacing of slot centers.
Some accessories are designed to fit on both Weaver and Picatinny rails; but most Picatinny devices will not fit on Weaver rails. As of May 2012, however, most mounting rails are cut to Picatinny standards, and many accessories come with the recoil pin cut to the Weaver-compatible diameter. Many rail-mounted accessories come with only a single recoil pin, avoiding the issue of differing slot spacing.