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Rifling of a 105 mm Royal Ordnance L7 tank gun Conventional rifling of a 90 mm M75 cannon (production year 1891, Austria-Hungary) Rifling in a GAU-8 autocannon. Rifling is the term for helical grooves machined into the internal surface of a firearms's barrel for imparting a spin to a projectile to improve its aerodynamic stability and accuracy.
Conventional eight groove rifling on the left, and octagonal polygonal rifling on the right. Polygonal rifling (/ p ə ˈ l ɪ ɡ ə n əl / pə-LIG-ə-nəl) is a type of gun barrel rifling where the traditional sharp-edged "lands and grooves" are replaced by less pronounced "hills and valleys", so the barrel bore has a polygonal (usually hexagonal or octagonal) cross-sectional profile.
The roller-delayed blowback StG 45(M) assault rifle prototypes proved pressure equalization fluting is desirable, since the breech of roller or lever-delayed blowback arms is opened whilst under very high internal cartridge case pressure that presses a spent (bloated) cartridge casing against the chamber walls which can cause significant ...
The West Point Foundry produced about 300 20-pounder Parrott rifles between September 1861 and July 1864. The gun barrels weighted between 1,635 lb (742 kg) and 1,815 lb (823 kg). The rifling consisted of five lands and grooves of right-hand gaining twist (increasing toward the muzzle) and the caliber (bore diameter) was 3.67 in (93 mm). [6]
Series 2, 3, and 4 all had 10 rifling grooves of right-hand twist. Various muzzle, trunnion, and breech stampings account for the other differences between Series 1, 2, 3 and 4 guns. [3] The Type 2 14-pounder James rifle measured 74 in (188.0 cm) from muzzle to the end of the knob and 69.75 in (177.2 cm) from muzzle to base, excluding the knob.
[36]: 32 The three main class characteristics of all bullets are the lands and grooves, the caliber of the bullet, and the rifling twist. [37] All three can be tied directly to the type of barrel that was used to fire the bullet. [37] The lands and grooves of barrel are the bumps and valleys created when the rifling is created. The caliber is ...
The class of firearm was originally termed the rifled gun, with the verb to rifle referring to the early modern machining process of creating grooves with cutting tools. By the 20th century, the weapon had become so common that the modern noun rifle is now often used for any log-shaped handheld ranged weapon designed for well-aimed discharge ...
Caliber/calibre: In small arms, the internal diameter of a firearm's barrel or a cartridge's bullet, usually expressed in millimeters or hundredths of an inch; in measuring rifled barrels this may be measured across the lands (.303 British) or grooves (.308 Winchester) or; a specific cartridge for which a firearm is chambered, such as .45 ACP or .357 Magnum.