ⓘ Rotation of ammunition is a term used with reference to guns. Projectiles intended for RML guns were at first fitted with a number of gun-metal studs arranged a ..


ⓘ Rotation of ammunition

Rotation of ammunition is a term used with reference to guns. Projectiles intended for RML guns were at first fitted with a number of gun-metal studs arranged around them in a spiral manner corresponding to the twist of rifling. This was defective, as it allowed, as in the old smooth-bore guns, the powder gas to escape by the clearance between the projectile and the bore, with a consequent loss of efficiency; it also quickly eroded the bore of the larger guns.

Later the rotation was effected by a cupped copper disc called an "automatic gas-check" attached to the base end of the projectile. The powder gas pressure expanded the rim of the gas check into the rifling grooves and prevented the escape of gas; it also firmly fixed the gas check to the projectile, thus causing it to rotate. A more regular and efficient action of the powder gas was thus ensured, with a corresponding greater range and an improvement in accuracy.

With the earlier Armstrong RBL or rifled breech loading guns the projectiles were coated with lead the late Lord Armstrongs system, the lead being forced through the rifling grooves by the pressure of the exploded powder gas. The lead coating is, however, too soft with the higher velocities of modern B.L. guns.

Vavasseur devised the plan of fitting by hydraulic pressure a copper "driving band" into a groove cut around the body of the projectile. This is now universal. It not only fulfills the purpose of rotating the projectile, but renders possible the use of large charges of slow-burning explosive. The copper band, on being forced through the gun, gives rise to considerable resistance, which allows the propelling charge to burn properly and thus to exert its enormous force on the projectile.

The laws which govern projectile designs are not well-defined. Certain formulae are used which give the thickness of the shell walls for a known chamber pressure in the gun, and for a particular stress on the shell material. The exact proportions of the shell depend, however, greatly on experimental knowledge.

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  • accuracy. Before long, studless ammunition was being manufactured for these guns, using gas - checks for projectile rotation Gas - checks also facilitated a
  • initiate gun rotation allowing the first rounds to be chambered and fired. The initial M61 used linked, belted ammunition but the ejection of spent links
  • Memoranda of Trajectory, and Description of Ammunition Washington: U.S. Government Printing Office. Revised U.S. Army description of the M1892 series of revolvers
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  • enclosed within a jacket of stronger mild steel or copper alloyed with nickel or zinc to reliably impart stabilizing rotation in rifled barrels. The lead - alloy
  • projectile of rifled muzzle - loading RML artillery, sealing the escape of gas between the projectile and the barrel and imparting axial rotation to the
  • a German design from Rheinische Metallwarenfabrik Ehrhardt for which ammunition could not be procured. It was a rigid - recoil, rifled, muzzle - loading weapon
  • standard M10 using the same type of ammunition APCBC would penetrate 98 mm of armour at 500 m at a 30 - degree angle, and 88 mm of armour at 1, 000 metres at