Sunday, May 5, 2013

Picatinny vs. Weaver – What’s the Difference?

Picatinny rails allow for universal mounting of grips, lights, optics and other accessories.

What is the difference between a Picatinny rail and a Weaver rail? They look a lot alike, but they aren't exactly interchangeable. In hopes that you won’t make the same mistake I have, here is a bit of history and an explanation of the differences between Picatinny and Weaver.

Until a few years ago, I’d never heard of a Picatinny. You have to remember, I’ve just gotten back into shooting in the last 5 years. Up until then, the only thing I had ever had mounted to a rifle was a 4x40 scope on a Marlin 336C .30-30 hunting rifle. Back then “the” mount to have was a Weaver.

Apparently while I was playing Rumpelstiltskin in the early 90’s, the technology of optics was growing in leaps and bounds. Up to that point, there was no standard mount. All the manufacturers pretty much did their own thing. Well, along comes Uncle Sam and he wants a quick method of changing optics and accessories while maintaining accuracy. They turned to Picatinny Arsenal in New Jersey for the solution.

What the arsenal did was gather a sample of the different mounts and more or less found an average of them all, tweaked it a bit here and there, and came up with the Mil-Std-1913 Picatinny Rail. It turns out that their rail is very close to the Weaver design.

The only real difference is the recoil lug slots on the Picatinny are slightly wider than weavers and the spacing between these lugs is more consistent. Picatinny slots are 0.206” wide and spaced 0.394” apart between centers. The Weaver slots are 0.180” wide and there is no consistency in the spacing since most mounts were made for a specific piece of equipment.

Are Picatinny and Weaver interchangeable? Here is where it gets tricky. My single experience before learning the difference says, “NO!” But generally speaking, Weaver mounts will Picatinny rails, and Picatinny mounts are not likely to fit Weaver rails. There are exceptions to every rule, but to play it safe, if you are accessorizing a Picatinny rail, buy only Picatinny mount accessories. If you’re outfitting a Weaver rail, buy Weaver mount accessories. It will save you a lot of fussing and cussing.

Be safe.


  1. Thanks for the first real clear explanation I can find on the slot dimensions! I bought a Clark Custom barrel for a S&W Model 41 with an integral Picatinny (style) scope base, style is how Clark describes this feature. I then bought a Vortex red dot with a picatinny mount and its recoil lug will not fit the slot. I'm going to mic it later but I'll bet it's .206" If so, Vortex got it right and Clark did not.

  2. Update to my last post: Vortex Venom recoil lug measures .198" so they got it right, it will fit a picatinny base. My Clark Custom Model 41 Match barrel with Picatinny style Scope base as an integral part of the barrel, slots measure .160", clearly NOT Picatinny standard. A weaver base works on it. Why they don't call it that, I don't know but it would have saved me some grief and $!