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Long recoil operation is found primarily in shotguns, particularly ones based on John Browning's Auto-5 action. In 1885 a locked breech, long recoil action was patented by the Britons Schlund and Arthur. [9] In a long recoil action, the barrel and bolt remain locked together during recoil, compressing the recoil springs.
A 12-gauge shotgun, nominally 18.5 mm (0.73 in), can range from a tight 18 mm (0.71 in) to an extreme overbore of 20 mm (0.79 in). Some also claim an increased velocity with the overbored barrels, up to 15 m/s (49 ft/s), which is due to the larger swept volume of the overbored barrel.
The mount height itself, that is the distance from the top of rail to center of scope, varies, but typically lies around 36–38 mm (1.4–1.5 in) (higher and lower mounts are also readily available). In total, this gives a typical scoped AR-style rifle a height over bore of around 67–69 mm (2.6–2.7 in).
The nature of the recoil process is determined by the force of the expanding gases in the barrel upon the gun (recoil force), which is equal and opposite to the force upon the ejecta. It is also determined by the counter-recoil force applied to the gun (e.g. an operator's hand or shoulder, or a mount).
Therefore, when the barrel recoils the inertial force from the breech produces a moment on the rear end of the barrel. This causes a wave to travel down the barrel which quickly overtakes the shot and results in a deflection of the muzzle before shot exit. Figure 6 shows the typical response of a tank gun barrel for an off-axis breech.
The AA-12 (Auto Assault - 12), originally designed and known as the Atchisson Assault Shotgun, is a fully automatic combat shotgun developed in 1972 by Maxwell Atchisson. . However, the original development by Atchisson seems to have produced only a few guns at prototype-level, with the development that ultimately led to the gun entering the market being done later by Military Police Systems ...
The Kord-12.7 mm heavy machine gun is a Russian design that entered service in 1998 [3] replacing the older NSV machine gun.Externally the weapon resembles the NSV; however, the internal mechanism has been extensively reworked, changing from a horizontally pivoting breech block to a rotating bolt design. [3]
Military use of combat shotguns through the 20th century has created a need for ammunition maximizing the combat effectiveness of such weapons within the limitations of international law. 12-gauge has been widely accepted as an appropriate bore diameter to provide an effective number of projectiles within an acceptable recoil. Early 12-gauge ...