What is the difference between the “Picatinny” (M1913) mounting rail and the “Weaver” mounts?
A. The so called “Picatinny Rail” is a standardized mounting system for small arms accessories used by NATO and the US military. The term “Picatinny” comes from the Picatinny Arsenal located in New Jersey, who developed the official specification known as MIL-STD-1913 which specifies the dimensions and tolerances required. The cross sectional profile of the M1913 and Weaver systems are virtually identical. The main difference lies in the placement and the width of the grooves. M1913 grooves are .206″ (5.23 mm) wide and have a center-to-center distance of .394″ (10 mm). The placement of these grooves has to be consistent in order for it to be a true “Picatinny” M1913 system. Weaver rails have .180″ ( 4.57 mm) recoil grooves and are not necessarily consistent in a center-to-center measurement from one groove to the next. Frequently, a Weaver system has a specific application that it is machined for, so interchangeability is not necessarily an issue. A MIL-STD-1913 system must adhere to t
