Question: are all picatinny rails the same?
Answer: because the Picatinny locking slot width is 0.206 in (5.232 mm) vs the . 180 width of the Weaver, and the spacing of slot centers is 0.394 in (10.008 mm). Because of this, with devices that use only one locking slot, Weaver devices will fit on Picatinny rails, but Picatinny devices will not always fit on Weaver rails.