You’ve just bought a rifle with one of those funny scope rails on it… is it Weaver or Picatinny? What’s the difference, and does it matter? Mike Morton reveals all…
The Weaver and Picatinny systems are very similar, both using a slotted rail that fulfils several roles. First, the slot provides an anchor point for the scope mount. Weaver/Picatinny mounts use a clamping system, just like a dovetail rail, but also make use of a bar which drops into one of the slots on the rail. This is the biggest draw of the Weaver/Picatinny system – it prevents the scope mount from creeping under recoil – and this works for each and every slot, not just the typical arrestor hole found on a springer or gas ram.
The slotted system also means you can remove your optic then put it back in the same slots with minimal shift in zero. This is especially useful if you intend to swap scopes fairly frequently.
The Weaver system, which has been around for decades, and the Picatinny, a US military-specification system that’s only been with us since 1995, are not the same, however. While the profile of the two systems is identical, the difference lies with the dimensions of the slots and their spacing on the rail. Picatinny slots are 0.206in wide and have a centre-to-centre spacing of 0.394in. The Picatinny system, named after Picatinny Arsenal in New Jersey, conforms to a military standard and so slot placement is consistent. The slots in a Weaver rail are just 0.18in wide and there is no agreed standard of spacing.
What does this mean for the airgun shooter? Not that much. True Weaver mounts will usually fit a Picatinny rail, as it has the larger slot, while true Picatinny mounts, being designed for the larger Picatinny slot, will usually not fit the smaller slots of the Weaver rail. However, scope mount manufacturers usually build their mounts to Weaver standard so they will happily fit both. The issue of the spacing between the slots is only a problem if you intend to use a one-piece mount. You haven’t said what type of rifle you have, but I’m sure you’ll soon see how easy it is to mount a scope with this system, and you’ll no doubt appreciate the anti-recoil properties of the rail.