All you need now is a scope base and you will be set to mount the scope on your favorite firearm.
When you start looking for scope bases, you will find two styles that look the same in the pictures, but are not the same.
One is called Weaver and the other Picatinny (MIL-STD-1913). These two rails, in many cases, can be used interchangeably.
Weaver vs. Picatinny: What’s the Difference?
The main differences between the Weaver and the Picatinny rails are the size of the cross slots and the slot spacing.
Weaver rails have a slot width of 0.180″ (4.572 mm), but are not necessarily consistent in the spacing of slot centers.
The Picatinny rail has a slot width of 0.206″ (5.232 mm) and the spacing of slot centers is always 0.394″ (10.008 mm).
Because of this, Weaver devices will fit on Picatinny rails, but Picatinny devices will not always fit on Weaver rails.
So those Weaver-style rings that came with your new scope will work on both styles of rails.
If the scope has been supplied with Picatinny-style rings, you will most likely be limited to only the Picatinny mount.
The difference between Weaver and Picatinny Rails is fairly minute, so if you are capable with a Dremel or file you may be able to make Picatinny devices fit on a Weaver rail.
Weaver Rail Basics
Weaver Optics has produced scopes for decades. The founder, William Ralph Weaver, also designed the Weaver rail as a mounting system for his scopes. The Weaver rail came before the Picatinny.
Additionally, when Weaver rails were introduced, they were made in two separate pieces. One piece would go on the front of the receiver and the other would attach to the rear for scope mounting.
This two-piece design allowed the bolt opening to be free from obstructions, allowing cartridges to be inserted easily and for the use of stripper clips.
Now, Weaver rails can be found in both one-piece and two-piece variants depending on your preferences and needs.
Picatinny Rail Basics
Picatinny mounts and rings will most commonly be found on products that were originally designed for military use and have found their way into the civilian market.
For instance, the top rail on an AR-15 (the civilian version of the U.S. M16 battle rifle) flattop receiver is a Picatinny rail. You are able to use both styles of rings on this rifle.
Some manufacturers include an accessory rail, but don’t use the Picatinny design. For example, GLOCK and SIG Sauer handguns have their own proprietary rail designs that are not interchangeable with the Picatinny rail.
However, many companies design their products to be compatible with both different styles of rails.
Conclusion: Weaver Rails vs. Picatinny Rails
Both of these rail systems have their share of popularity among shooters, but you’re more likely to find a Picatinny rail on modern firearms.
The popularity of the Picatinny rail is partially because of the adoption of the rail by the U.S. Military in 1995, but also because the consistent spacing makes them a better option for swapping accessories between guns.
Which style of rail do you prefer and why? Let us know in the comments section below!
Editor’s note: This post was originally published in April of 2011. It has been completely revamped and updated for accuracy and clarity.