Rotation of ammunition

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Examples of projectiles with copper rings, shown in The Engineer, November 20, 1908. Projectiles with copper rings - The Engineer 1908-11-20.png
Examples of projectiles with copper rings, shown in The Engineer, November 20, 1908.

Rotation of ammunition is a term used with reference to guns. Projectiles intended for RML (rifled muzzle-loading) 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. Invented in mid-1840s by Giovanni Cavalli, this method was defective, as it allowed, as in the old smooth-bore guns, the powder gas to escape by the clearance (called "windage") between the projectile and the bore, with a consequent loss of efficiency; it also quickly eroded the bore of the larger guns. [1] Multiple solution to the problems were invented in two following decades, both for muzzle-loaders and breech-loaders.

In 1855 Andrew Hotchkiss patented an RML projectile, in which two parts squeezed a lead ring to obturate the barrel under the pressure of gunpowder fumes. [2] After his death in 1858 his brother Benjamin, later a renowned arms designer and industrialist, adapted the design to practical use, [3] and the Union Army fired them during the American Civil War.

In the same year Joseph Whitworth patented polygonal projectiles mechanically fitted with polygonal rifling in the muzzle-loaders. They were used in the same war by the Confederates.

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. [1]

With the earlier Armstrong (RBL or rifled breech loading) guns the projectiles were coated with lead (the late Lord Armstrong's 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. [1]

Vavasseur devised the plan of fitting by hydraulic pressure a copper "driving band" into a groove cut around the body of the projectile and patented it in 1866. This is now universal.[ citation needed ] 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. [1]

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. [1]

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A rifle is a long-barreled firearm designed for accurate shooting, with a barrel that has a helical pattern of grooves (rifling) cut into the bore wall. In keeping with their focus on accuracy, rifles are typically designed to be held with both hands and braced firmly against the shooter's shoulder via a buttstock for stability during shooting. Rifles are used extensively in warfare, self defense, law enforcement, crime, hunting, and shooting sports.

Bullet Projectile propelled by a firearm, sling, or air gun

A bullet is a kinetic projectile, a component of firearm ammunition that is shot from a gun barrel. Bullets are made of a variety of materials, such as copper, lead, steel, polymer, rubber and even wax. Bullets are made in various shapes and constructions, including specialized functions such as hunting, target shooting, training and combat. Bullets are often tapered, making them more aerodynamic. Bullet sizes are expressed by their weights and diameters in both imperial and metric measurement systems. For example: 55 grain .223 caliber bullets are of the same weight and caliber as 3.56 gram 5.56mm caliber bullets. Bullets do not normally contain explosives but strike or damage the intended target by transferring kinetic energy upon impact and penetration. Bullets shot by firearms can be used for target practice or to injure or kill animals or people.

Rifling Gunsmithing technique

In firearms, rifling is machining helical grooves into the internal (bore) surface of a gun's barrel for the purpose of exerting torque and thus imparting a spin to a projectile around its longitudinal axis during shooting to stabilize the projectile longitudinally by conservation of angular momentum, improving its aerodynamic stability and accuracy over smoothbore designs.

Driving band

A driving band or rotating band is a band of soft metal near the base of an artillery shell, often made of gilding metal, copper, or lead. When the shell is fired, the pressure of the propellant swages the metal into the rifling of the barrel and forms a seal; this seal prevents the gases from blowing past the shell, and engages the barrel's rifling to spin-stabilize the shell.

Gun barrel Firearm component which guides the projectile during acceleration

A gun barrel is a crucial part of gun-type weapons such as small firearms, artillery pieces and air guns. It is the straight shooting tube, usually made of rigid high-strength metal, through which a contained rapid expansion of high-pressure gas(es) is used to propel a projectile out of the front end (muzzle) at a high velocity. The hollow interior of the barrel is called the bore, and the diameter of the bore is called its caliber, usually measured in inches or millimetres.

Internal ballistics, a subfield of ballistics, is the study of the propulsion of a projectile.

Rifled breech loader Class of artillery

A rifled breech loader (RBL) is an artillery piece which, unlike the smoothbore cannon and rifled muzzle loader (RML) which preceded it, has rifling in the barrel and is loaded from the breech at the rear of the gun.

This article explains terms used for the British Armed Forces' ordnance and also ammunition. The terms may have slightly different meanings in the military of other countries.

Polygonal rifling

Polygonal rifling 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 cross-sectional profile.

RBL 7-inch Armstrong gun Naval gun

The Armstrong RBL 7-inch gun, also known as the 110-pounder, was an early attempt to use William Armstrong's new and innovative rifled breechloading mechanism for heavy rifled guns.

A muzzle-loading rifle is a muzzle-loaded small arm or artillery piece that has a rifled barrel rather than a smoothbore. The term "rifled muzzle loader" typically is used to describe a type of artillery piece, although it is technically accurate for small arms as well. A shoulder arm is typically just called a "rifle", as almost all small arms were rifled by the time breechloading became prevalent. Muzzle and breechloading artillery served together for several decades, making a clear distinction more important. In the case of artillery, the abbreviation "RML" is often prefixed to the guns designation; a Rifled breech loader would be "RBL", or often just "BL", since smoothbore breechloading artillery is almost nonexistent. A muzzle loading weapon is loaded through the muzzle, or front of the barrel. This is the opposite of a breech-loading weapon or rifled breechloader (RBL), which is loaded from the breech-end of the barrel. The rifling grooves cut on the inside of the barrel cause the projectile to spin rapidly in flight, giving it greater stability and hence range and accuracy than smoothbore guns. Hand held rifles were well-developed by the 1740s. A popularly recognizable form of the "muzzleloader" is the Kentucky Rifle, which was actually developed in Pennsylvania. The American Longrifle evolved from the German "Jäger" rifle.

Armstrong gun

An Armstrong gun was a uniquely designed type of rifled breech-loading field and heavy gun designed by Sir William Armstrong and manufactured in England beginning in 1855 by the Elswick Ordnance Company and the Royal Arsenal at Woolwich. Such guns involved a built-up gun construction system of a wrought-iron tube surrounded by a number of wrought-iron strengthening coils shrunk over the inner tube to keep it under compression.

RML 9-inch 12-ton gun Naval gun

The RML 9-inch guns Mark I – Mark VI were large rifled muzzle-loading guns of the 1860s used as primary armament on smaller British ironclad battleships and secondary armament on larger battleships, and also ashore for coast defence. It should not be confused with the RML 9-inch Armstrong Gun, used by the Dutch navy, the Spanish Navy, and other navies.

RML 12.5-inch 38-ton gun Naval gun

The RML 12.5-inch guns were large rifled muzzle-loading guns designed for British battleships and were also employed for coast defence.

RML 16-inch 80-ton gun Naval gun

RML 16-inch 80-ton guns were large rifled muzzle-loading guns intended to give the largest British battleships parity with the large guns being mounted by Italian and French ships in the Mediterranean Sea in the 1870s.

Caliber (artillery) Internal diameter of a gun barrel

In artillery, caliber or calibre is the internal diameter of a gun barrel, or - by extension - a relative measure of the barrel length.

RML 8-inch 9-ton gun Naval gun

The British RML 8-inch 9-ton guns Mark I – Mark III were medium rifled muzzle-loading guns used to arm smaller ironclad warships and coast defence batteries in the later 19th century.

Gas-checks were attachments to ammunition that revolutionised the performance of RML heavy guns. The first generation of RML heavy guns began entering service in about 1865. They all had Woolwich rifling and relied on studs on the projectiles for rotation. Gas-checks were first introduced in 1878 or soon after. They significantly reduced wear on the guns while also increasing their range and accuracy. Before long, studless ammunition was being manufactured for these guns, using gas-checks for projectile rotation. Gas-checks also facilitated a switch to the second generation of RML guns which used polygroove rifling and only supported studless ammunition.

RML 8-inch howitzer Howitzer

The RML 8-inch howitzer was a British Rifled, Muzzle Loading (RML) Howitzer manufactured in England in the 19th century, which fired a projectile weighing approximately 180 pounds (82 kg). It was used in siege batteries and in fortifications.

RML 6.6-inch howitzer Howitzer

The RML 6.6 inch howitzer was a British Rifled, Muzzle Loading (RML) Howitzer manufactured in England in the 19th century, which fired a projectile weighing approximately 100 pounds (45 kg). It was used in siege batteries and in fortifications.

References

  1. 1 2 3 4 5 Chisholm 1911.
  2. U.S. Patent 13679A
  3. "Ordnance Geniuses: The Hotchkiss Brothers and their projectiles, Part 1". 23 May 2016.
Attribution

Wikisource-logo.svg This article incorporates text from a publication now in the public domain : Chisholm, Hugh, ed. (1911). "Ammunition". Encyclopædia Britannica . Vol. 1 (11th ed.). Cambridge University Press.