Polygon run
A polygonal rifling is a firearms - run with polygonal profile. The principle of the polygon course was proposed by the Englishman Joseph Whitworth as early as 1853 , rejected by the British Army because of the costs, but later used with success by the Whitworth Sharpshooters in the American Civil War .
features
A rounded polygon (Greek polygon ) can be seen when looking through a polygon (see graphic on the right); it continues helically through the entire course. In this way, the projectile driven through the barrel is set into rotation around its longitudinal axis and its flight is stabilized.
In contrast, conventional drawn barrels have a round profile, the twist is achieved by helical notches: so-called fields and trains .
Since the bullet takes up a larger proportion of the barrel cross-section in polygonal barrels, gas losses between bullet and barrel are significantly lower, which leads to a higher muzzle velocity. In addition, polygon barrels have less wear and tear and thus a higher life expectancy and are more blast-proof due to the lower notch effect . They are also easier to clean than runs with trains and fields. However, polygon barrels can transfer less rotational forces (twist) to the projectile than rifled barrels.
After passing the barrel, there are no notches on the storey itself, but a polygonal profile corresponding to the inside of the barrel . The uncharacteristic deformation of the projectiles makes forensic examinations and assignments to certain weapons extremely difficult and usually impossible. In the case of rifled barrels, on the other hand, the projectiles have deformations that suggest a specific weapon, since the fields and trains acting on the projectile are worn differently for each weapon.
use
Initially only developed and used specifically for military purposes and demands, there are now polygonal barrels for high-quality handguns (for example the HK USP series from Heckler & Koch , except HK P8 , with hexagonal barrel, the HK P9S , the Glock pistols and the SIG Sauer P228 ) and hunting rifles (e.g. Heym SR 20 repeater with a square barrel). Since polygon barrels transmit comparatively little twist to the projectile, they are primarily used for handguns for projectiles with a lower mass moment of inertia and not for large-caliber guns.
literature
- Daniel Faninger: weapon technology. (History and technology of polygon runs), 2000, HTBLA-Ferlach, (Higher Technical Federal College Ferlach / Austria)