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O ratio is also used to predict barrel life in cartridges of the same caliber, but not of different calibres, since the ratio is an extensive quantity that does not correlate to temperature or pressure (e.g. a .50 cal straight cartridge may have the same overbore as a highly necked down .17 cal cartridge).
A choke is designed to alter or shape the distribution of the shot as it leaves the firearm. For shooting most game birds and clay pigeons, a desirable pattern is one that is as large as possible while being dense enough to ensure multiple hits on the target, at a particular range.
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 bore axis of a firearm is the longitudinal axis through the geometric center of the gun barrel. In a rifled barrel, the projectile (bullet/ball, pellet or slug) will spin around the bore axis as it goes through the barrel. Boresighting is a process of placing one's line of sight down along the bore axis.
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.
Before the barrel can release the bullet in a consistent manner, it must grip the bullet in a consistent manner. The part of the barrel between where the bullet exits the cartridge, and engages the rifling, is called the "throat", and the length of the throat is the freebore. In some firearms, the freebore is zero as the act of chambering the ...
US dry barrel: 7,056 cubic inches (115.6 litres; 3.3 US bushels) . Defined as length of stave 28 + 1 ⁄ 2 in (72 cm), diameter of head 17 + 1 ⁄ 8 in (43 cm), distance between heads 26 in (66 cm), circumference of bulge 64 in (160 cm) outside measurement; representing as nearly as possible 7,056 cubic inches; and the thickness of staves not greater than 4 ⁄ 10 in (10 mm) [2] (diameter ≈ ...
A muzzle brake or recoil compensator is a device connected to, or a feature integral (ported barrel) to the construction of, the muzzle or barrel of a firearm or cannon that is intended to redirect a portion of propellant gases to counter recoil and unwanted muzzle rise. [1] Barrels with an integral muzzle brake are often said to be ported.