A Weaver rail mount is a system to connect telescopic sights (often via a scope mount) and other accessories to firearms and certain crossbows. [1] It uses a pair of parallel rails and several slots perpendicular to these rails.
The later Picatinny rail, developed by the US military, is a development of the key concepts of the Weaver system, and they are partially compatible. [2]
The Weaver mount was developed by William Ralph Weaver (1905 – 8 November 1975) at his telescopic sight company W.R. Weaver Co., which he founded in 1930. [3] Previous systems included the Leupold/Redfield mounts. [4] Compared to the Leupold mount, the Weaver rail is not as strong and cannot be adjusted for windage. [4]
W.R. Weaver Co. became Weaver Optics, and was a subsidiary of Meade Instruments Corporation from 2002 to 2008, when it was on-sold to become part of Alliant Techsystems's Security and Sporting division in Onalaska, Wisconsin.
Older Weaver systems used two pieces mounted a distance apart from one another, typically on the receiver of a rifle over the bolt opening, where the cartridge would be inserted and/or ejected. However, alignment problems of the two piece system can put undue stress on a rifle scope and cause problems between the scope and rifle barrel parallels and bullet Point Of Impact (POI). The two piece system must be mounted with exacting tolerances to ensure perfect alignment, using a scope alignment device called Alignment Sleeves.
The two piece type can be problematic on some rifles that do not allow for the two pieces to be mounted due to metal thickness of the receiver, or other issues of receiver length that will not allow for proper distance to hold the scope. With the later one piece approach, the rail system remains consistent in alignment.
The slots on a Weaver system are primarily used as a clearance of the locking screw that tightens the clamp to the rail. Some Weaver-type accessories have a bar that fits inside the machined slots on the rails while many others do not.
Weaver rails have a slot width of 0.180 in (4.57 mm), but are not necessarily consistent in the spacing of slot centers. [5]
The lack of a locking bar on many Weaver-type accessories lends to another alignment issue: side-to-side canting. Although this issue is not common, it can be very problematic especially with scopes. Because scopes need to be mounted to a rifle in perfect parallel to the barrel, and to ensure the cross hairs indicate a point of aim (POA) exactly at a bullet's point of impact (POI) at a known distance, a small variation of even one quarter of one degree can cause massive problems at longer ranges. The locking bar holds the mount in a perfect 90 degrees to the rail system, whereas a non-locking bar system can cant to the left or right.
This canting, sometimes called jamming of surfaces, is caused by not matching the clamping surface perfectly to the rail. When tightened down, stress exerted on the base can cause the scope's POA to be off from the POI by as much as several feet at 100–200 yards, and gets progressively worse with greater distance. Lower grade materials used in manufacturing of scope bases, inconsistent design tolerances from one manufacturer to another, and other factors can cause twisting stress and cause the mount to move out of parallel with the rifle barrel. The locking bar system allows for even stress to be distributed and prevent canting of the scope mount.
Another form of scope canting is caused by the rings themselves. Many Weaver-type mounts, including many Picatinny-type scope rings and even the Redfield Type, have either two or four screws on top of the scope ring that hold the scope in place. Both the Weaver and Picatinny clamp systems have a screw side and a clamp side. With the two-screw style, the ring usually aligns well but does not have the strength of the four screw system. Many times, when tightening the screws of the four screw type, the scope can twist in place, causing misalignment. Tightening the mounts in an “X” pattern and usually starting opposite of the outside clamp side. Holding the scope slightly to the opposite side while tightening the screws usually allows for proper alignment of the scope to barrel parallel.
The military standard, MIL-STD-1913 "Picatinny rails" date from the mid-1990s and have very strict military standard dimensions and tolerances. The Picatinny rail has a similar profile to the Weaver, but the recoil groove width of the Picatinny rail is 0.206 in (5.23 mm) versus 0.180 in (4.57 mm) of the Weaver rail/mount, and by contrast with the Weaver, the spacing of the Picatinny recoil groove centers is consistent, at 0.394 in (10.01 mm). [5]
Many rail-grabber-mounted accessories can be used on either type of rail, and accessories designed for a Weaver system will always (SWP) fit Picatinny rails – although not vice versa because the Picatinny locking slot width is 0.206 in (5.232 mm) vs the .180 width of the Weaver, and the spacing of slot centers is 0.394 in (10.008 mm). [5] Because of this, with devices that use only one locking slot, Weaver devices will fit on Picatinny rails, but Picatinny devices will not always fit on Weaver rails. [5]
Another difference is that Weaver rails are continuous with only two to four recoil grooves cut, while Picatinny rails have recoil grooves cut across the entire length of the rail at the above noted spacing (like a dotted line). This allows for more mounting position flexibility and also helps to neutralize expansion caused by barrel heating.
The Springfield Armory M1A is a semi-automatic rifle made by Springfield Armory, Inc., beginning in 1971, based on the M14 rifle, for the civilian and law enforcement markets in the United States. "M1A" is a proprietary name for Springfield Armory's M14-pattern rifle. Early M1A rifles were built with surplus G.I. parts until Springfield Armory, Inc. began manufacturing their own. Robert Reese bought Springfield Armory from Elmer Ballance and moved the manufacturing from Devine, Texas to Geneseo, Illinois in 1974.
The Desert Eagle or "Deagle" is a single-action, gas-operated, semi-automatic pistol capable of chambering the .50 Action Express, the largest centerfire cartridge of any magazine-fed, self-loading pistol and famous for other large caliber chamberings.
The Accuracy International Arctic Warfare rifle is a bolt-action sniper rifle designed and manufactured by the British company Accuracy International. It has proved popular as a civilian, police, and military rifle since its introduction in the 1980s. The rifles have features that improve performance in extremely cold conditions without impairing operation in less extreme conditions.
The 1913 rail is an American rail integration system designed by Richard Swan that provides a mounting platform for firearm accessories. It forms part of the NATO standard STANAG 2324 rail. It was originally used for mounting of telescopic sights atop the receivers of larger caliber rifles.
A telescopic sight, commonly called a scope informally, is an optical sighting device based on a refracting telescope. It is equipped with some form of a referencing pattern – known as a reticle – mounted in a focally appropriate position in its optical system to provide an accurate point of aim. Telescopic sights are used with all types of systems that require magnification in addition to reliable visual aiming, as opposed to non-magnifying iron sights, reflector (reflex) sights, holographic sights or laser sights, and are most commonly found on long-barrel firearms, particularly rifles, usually via a scope mount. Similar devices are also found on other platforms such as artillery, tanks and even aircraft. The optical components may be combined with optoelectronics to add night vision or smart device features.
The Ares Defense Shrike 5.56 is an air-cooled, dual-feed light machine gun/rifle for semi or full-auto configurations that fires the 5.56×45mm NATO cartridge. The Shrike 5.56 is sold as either as a complete weapon, or as an upper receiver "performance upgrade kit" to existing AR-15 and M16-type service rifles and carbines. The name comes from the Shrike, a carnivorous passerine bird, and was designed by Geoffrey Herring.
Aimpoint AB is a Swedish optics company based in Malmö, Sweden that manufactures red dot sights.
The ArmaLite AR-7 Explorer is a semi-automatic firearm in .22 Long Rifle caliber, developed in 1959 from the AR-5 that was adopted by the U.S. Air Force as a pilot and aircrew survival weapon. The AR-7 was adopted and modified by the Israeli Air Force as an aircrew survival weapon in the 1980s.
A rail integration system is a generic term for any standardized attachment system for mounting firearm accessories via bar-like straight brackets often with regularly spaced slots.
The SG 550 is an assault rifle manufactured by SIG Sauer AG in Switzerland. "SG" is an abbreviation for Sturmgewehr. The rifle is based on the earlier 5.56×45mm NATO SIG SG 540.
The APR is a bolt-action sniper rifle designed by the Thun-based Brügger & Thomet in 2003 as an evolution of the French PGM Précision.
The C14 Timberwolf MRSWS is a bolt-action sniper rifle built by the Canadian arms company PGW Defence Technologies Inc. In 2005 they won the contract to supply the Canadian Forces Land Command with the C14 Timberwolf MRSWS for $4.5 million.
A red dot sight is a common classification for a non-magnifying reflector sight that provides an illuminated red dot to the user as a point of aim. A standard design uses a red light-emitting diode (LED) at the focus of collimating optics, which generates a dot-style illuminated reticle that stays in alignment with the firearm the sight is attached to, regardless of eye position.
KeyMod is a universal interface system for firearm accessory components. The concept was first created by VLTOR Weapon Systems of Tucson, Arizona, and released through Noveske Rifleworks of Grants Pass, Oregon, before being published open sourced in the public domain for adoption by the entire firearms accessory industry. The name "KeyMod" was coined by Eric Kincel following the naming trend of other VLTOR accessories with the suffix "Mod" meaning modular, and "Key" being a reference to the key-hole profile of the mounting slots.
M-LOK, for Modular Lock, is a firearm rail interface system developed and patented by Magpul Industries. The license is free-of-charge, but subject to an approval process.
The UIT rail, also known as Anschutz rail, is a standard used for mounting slings and other gun accessories in competition shooting, and is essentially a T-slot track shaped aluminium extrusion profile accepting attachments in the form of T-slot nuts, or similar.
A dovetail rail or dovetail mount can refer to several types of sliding rail system found on firearms, primarily for mounting telescopic sights. Colloquially, the term dovetail rail usually refer to any straight mounting bracket with an inverted trapezoid (dovetail) cross-section running parallel to the bore for mounting a scope or diopter sight to a rifle. These are sometimes also called "tip-off" mounts, and allow the user to easily take on or off the sight. Dovetail mount can also refer to a dovetail track running perpendicular to the bore.
Zeiss inner rail, generally simply referred to as Zeiss rail, is a ringless scope sight mounting system introduced by Zeiss in 1990 as an alternative to traditional ring mounts. A patent was granted in 1992, and the patent expired in 2008. The mounting system is now also offered on sights sold by other major manufacturers, such as Blaser, Leica, Minox, Meopta, Nikon, Noblex, Schmidt & Bender and Steiner. The system has so far seen most use on the European high-end market.
The Sauer 404 is a lightweight bolt-action rifle manufactured by Sauer & Sohn. The rifle was launched in 2015, and is a direct successor of the Sauer 202. It has a modular construction allowing for easy replacement of components and changing between barrels with different chamberings. This 404 is currently made in a large selection of chamberings and a modular barrel-change system allows changing between chamberings.
Scope mounts are rigid implements used to attach (typically) a telescopic sight or other types of optical sights onto a firearm. The mount can be made integral to the scope body or, more commonly, an external fitting that clamp onto the scope tube via screw-tightened rings. The scope and mount are then fastened onto compatible interfaces on the weapon. Words such as mounts and bases are used somewhat loosely, and can refer to several different parts which are either used together or in place of each other as ways to mount optical sights to firearms.