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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 gun used polygonal rifling, a principle invented by Whitworth in 1853.The concept was to use the hexagon to impart a very rapid spin to the projectile. The method of manufacturing the rifling was thus described by the Report of the Armstrong & Whitworth Committee of the British War Office (1866):
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.
The Whitworth rifle was designed by Sir Joseph Whitworth, a prominent British engineer and entrepreneur. Whitworth had experimented with cannons using polygonal rifling instead of traditional rifled barrels, which was patented in 1854. The hexagonal polygonal rifling meant that the projectile did not have to bite into grooves as was done with ...
Only 48,817 HK91s were imported into the U.S. prior to 1989. The retail price for an HK91 in the late 1970s was roughly $380 for the standard A2 models and $50 more for the A3 version. Prior to 1979, H&K did limited production runs of HK91s with polygonal rifle barrels. These were only $10 more than their standard counterparts.
The companies that use polygonal rifling claim greater accuracy, lower friction, and less lead and/or copper buildup in the barrel. Traditional land and groove rifling is used in most competition firearms, however, so the advantages of polygonal rifling are unproven. There are four methods of rifling a barrel: A single point cutter is drawn ...
A rifle is a firearm designed to be fired from the shoulder, with a barrel that has a helical groove or pattern of grooves ("rifling") cut into the barrel walls.The raised areas of the rifling are called "lands," which make contact with the projectile (for small arms usage, called a bullet), imparting spin around an axis corresponding to the orientation of the weapon.
T91K3: The T91K3 features polygonal rifling which increases barrel life and improves accuracy. [7] The 205th Arsenal and the National Defense University are jointly developing a nickel-boron finish for the bolt carriers, which would allow the weapon to fire about 10,500 rounds without any lubrication whatsoever.