Peut-être que c'est un rail Weaver au lieu d'un Picatiny
The “Picatinny Rail” is a term that has evolved in the firearm industry from a military standard, specifically MIL-STD-1913 (AR) which was adopted on February 3, 1995. The title of the publication is “Dimensioning Of Accessory Mounting Rail For Small Arms Weapons” and this document specified exactly what the dimensions and tolerances were for any mounting systems that were to be submitted for acceptance by the military. The term “Picatinny” comes from the place of origin for this system, the Picatinny Arsenal located in New Jersey. MIL-STD-1913 specifies the dimensions required for consideration, including length, width, height, and angles and the tolerances allowed for each measurement. The key distinction of the MIL-STD-1913 lies in the specification for the profile and the recoil groove.
What are the differences between the “Picatinny” and the “Weaver” systems? The profile of the two systems is virtually identical. Depending on the quality of the machining done by the manufacturer, the two systems should be indistinguishable from the profile. The key difference lies in the placement of the recoil grooves and with width of the grooves. MIL-STD-1913 (Picatinny) grooves are .206” wide and have a center-to-center width of .394”. The placement of these grooves has to be consistent in order for it to be a true “Picatinny” MIL-STD system. Weaver systems have a .180” width of recoil groove and are not necessarily consistent in a center-to-center measurement from one groove to the next. In many instances, 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 the specifications listed above in order for it to be considered MIL-STD, since the military desires uniformity in the recoil grooves to allow for different systems to be mounted on the weapon with no concern for compatibility.
Now, what does this mean to you? Boiled down, it means that accessories designed for a Weaver system will, in most cases, fit on a “Picatinny” system. The reverse, however, is probably not the case. Due to the larger recoil groove, “Picatinny” accessories will not fit a Weaver system. There are, of course, exceptions to every rule, but for a good rule-of-thumb, “Picatinny” won’t fit Weaver, but Weaver will fit “Picatinny”.
La partie intéressante est à la fin : il y est dit clairement qu'il est possible de monter un collier Weaver sur un rail Picatinny mais que l'inverse n'est (en principe) pas possible.
Selon les normes de chacun de ces deux standards, les tenons de recul des colliers Picatinny, s'ils sont juste à la cote du standard, sont trop épais pour rentrer dans les entailles transversales d'un rail Weaver.
Les encoches du rail picatinny font, selon le standard, .206 inch (5,23mm) de large et celles du Weaver font seulement .180 inch (4,57mm), ce qui n'est donc pas assez large pour un tenon Picatinny.
NDLR : un petit coup de lime sur un tenon Picatinny, s'il est amovible, permet assez facilement de le ramener à une épaisseur compatible avec un rail Weaver.
Il suffit d'enlever les 6 à 7 dixièmes de millimètres d'épaisseur en trop.
Accueil 
Lun 29 Fév 2016 - 22:32
