Scope mount

Attachment interfaces for scope mounts vary according to weapon design and user choice.

Traditionally scope mounts are fastened onto firearms via tapped screw holes (usually on the receiver) and/or clamps (onto the barrel or stock).

Since the mid-20th century, dovetail rails, where the mount is slided over a straight dovetail bracket with an inverted isosceles trapezoid cross-section and fixed tight in position with clamping screws, became more common due to the ease of installation and removal.

These mounts are usually fastened with screws to specified tensions (which warrants the use of torque screwdrivers), but sometimes they are manually tightened via thumbscrews, and may even have Quick Release (QR) designs.

As of 2020, the Picatinny rail is arguably the most widespread scope mounting standard for new firearms, although there are many proprietary and brand-specific types of mounts that can either be used with Picatinny rails, or as completely different design alternatives (see the section on Link between scope and firearm).

After the patent expired in 2008, compatible scopes have been offered from manufacturers such as Blaser,[1] Leica, Minox, Meopta, Nikon,[2] Noblex (formerly Docter[3]), Schmidt & Bender[4] and Steiner.

[5] It has therefore, in some sense, become the de facto industry standard for scope mounting rails.

[11]) has a flat rail with many "teeth" as recoil lugs, and is only offered on scopes from Swarovski and its subsidiary Kahles.

A former competing standard was the halv-circle shaped Schmidt & Bender Convex rail[4] also introduced in 2005.

In contrast to the Zeiss and Swarovski systems, the S&B Convex rail had the possibility to add a cant to the scope when mounting, such that the reticle is not horizontal to the ground.

The XTR variant differs in that it has two circular cavities per ring assembly versus one.

Many European assemblies use M3.5 screws, such as SAKO Optilock, Recknagel and original CZ rings.

The Remington 700 Short Action (SA) scope base attachment pattern is particularly widespread, and is for example used on models such as:[54] The Remington 700 Long Action (LA) naturally has a longer distance between the front and rear screw holes, and therefore continuous scope mount assemblies for the 700 LA do not fit on the 700 SA nor the above-mentioned firearms.

Conversely, a slightly too large radius on the mount will result in just one point of contact and a less stable attachment.

In the table below, the radius refers to the curvature of the mounting surface on the receiver bridge.

In some cases, it may be relevant to add extra inclination to the scope to be able to shoot at longer (or shorter) distance.

For example, this is popular for long range shooting, where it is common to use a tilt of 6 mrad (20 MOA).