Caseless ammunition
Encyclopedia
Small arms
Small arms is a term of art used by armed forces to denote infantry weapons an individual soldier may carry. The description is usually limited to revolvers, pistols, submachine guns, carbines, assault rifles, battle rifles, multiple barrel firearms, sniper rifles, squad automatic weapons, light...
ammunition
Ammunition
Ammunition is a generic term derived from the French language la munition which embraced all material used for war , but which in time came to refer specifically to gunpowder and artillery. The collective term for all types of ammunition is munitions...
that eliminates the cartridge
Cartridge (firearms)
A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...
case that typically holds the primer, propellant, and projectile together as a unit. Caseless ammunition is an attempt to reduce the weight and cost of ammunition by dispensing with the case, which is typically precision made of brass
Brass
Brass is an alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties.In comparison, bronze is principally an alloy of copper and tin...
or steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
, as well as simplify the operation of repeating firearms by eliminating the need to extract and eject the empty case after firing.
History
Caseless ammunition, in the broad sense, is not a new concept. A number of early paper cartridgePaper cartridge
Paper cartridge refers to one of various types of small arms ammunition used before the advent of the metallic cartridge. These cartridges consisted of a paper cylinder or cone containing the bullet, gunpowder, and, in some cases, a primer or a lubricating and anti-fouling agent...
designs used a combustible "case", which left no significant residue in the action after firing; one of the earliest military breech-loading rifles, the Dreyse
Johann Nikolaus von Dreyse
Johann Nicolaus von Dreyse was a German firearms inventor and manufacturer. He is most famous for submitting the "Dreyse needle gun" in 1836 to the Prussian army, which was adopted for for service in December 1840 as the Leichte Perscussions-Gewehr M 1841—a name deliberately chosen to...
needle gun
Needle gun
The Dreyse needle-gun was a military breechloading rifle, famous as the main infantry weapon of the Prussians, who adopted it for service in 1848 as the Dreyse Zündnadelgewehr, or Prussian Model 1848...
, used such a cartridge. It contained the powder, primer, and sabot
Sabot
A sabot is a device used in a firearm or cannon to fire a projectile, such as a bullet, that is smaller than the bore diameter, or which must be held in a precise position. The term is also applied to a battery stub case, a device used similarly to make a small electrical battery usable in a...
ed bullet in a paper cartridge. This design was an evolution of earlier paper cartridges for externally primed muzzle loading firearms, and predated the wide adoption of the metallic cartridge case.
The first use of caseless ammunition for use in a repeating firearm was the Rocket Ball
Rocket Ball
This article is about a specific type of ammunition for firearms, For the sport known as rocket ball, see RocketBallThe Rocket Ball was one of the earliest forms of metallic cartridge for firearms, containing bullet and powder in a single, metal cased unit.-Construction:The Rocket Ball, patented in...
projectile patented by Walter Hunt
Walter Hunt
Walter Hunt was an American mechanic. He lived and worked in New York state. Through the course of his work he became renowned for being a prolific inventor, notably of the lockstitch sewing machine , safety pin , a forerunner of the Winchester repeating rifle, a successful flax spinner, knife...
in 1848. A charge of black powder was placed inside a hollow at the back of a specially shaped Minié ball
Minié ball
The Minié ball is a type of muzzle-loading spin-stabilising rifle bullet named after its co-developer, Claude-Étienne Minié, inventor of the Minié rifle...
. These rounds were used by Hunt in a prototype repeating lever action rifle. The later Volcanic cartridge by Smith & Wesson
Smith & Wesson
Smith & Wesson is the largest manufacturer of handguns in the United States. The corporate headquarters is in Springfield, Massachusetts. Founded in 1852, Smith & Wesson's pistols and revolvers have become standard issue to police and armed forces throughout the world...
added a primer to the Rocket Ball, and improved on the lever action design. Similar ammunition was used by the Volcanic Repeating Arms
Volcanic Repeating Arms
The Volcanic Repeating Arms Company was a company formed in 1855 by partners Horace Smith and Daniel B. Wesson to develop Walter Hunt's Rocket Ball ammunition and lever action mechanism. Volcanic made an improved version of the Rocket Ball ammunition, and a carbine and pistol version of the lever...
company for the Volcanic rifle.
During World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
, Germany began an intensive program to research and develop a practical caseless ammunition for military use, which was driven by the rising scarcity of metals, especially copper used to make cartridge cases. The Germans had some success, but not sufficient to produce a caseless cartridge system during the war.
Modern caseless ammunition
Modern caseless ammunition consists of a solid mass of propellant, originally nitrocelluloseNitrocellulose
Nitrocellulose is a highly flammable compound formed by nitrating cellulose through exposure to nitric acid or another powerful nitrating agent. When used as a propellant or low-order explosive, it is also known as guncotton...
, cast into shape to form the body of the cartridge, with cavities to accept the bullet and a primer, preferably combustible, which are glued into place. The completed cartridge might also contain a booster charge of powdered propellant, to help ignite the body and provide initial thrust to the bullet.
Many caseless cartridges are also telescoped, with the bulk of the bullet held within the body of the cartridge, to cut down on cartridge length. A shorter cartridge cuts down on the distance the firearm's action must reciprocate to load a new round, which allows for higher cyclic rates and greater probability of multiple hits on a target at long range. Lack of a case also reduces the weight of the cartridge substantially, especially in small bore rifles. For example, the caseless ammunition for the Voere VEC-91
Voere VEC-91
The Voere VEC-91, made by Voere, is the first commercial sporting rifle to combine caseless ammunition and electronic firing. Depending upon its chambering, it fires a 5.7 mm or 6 mm projectile at speeds of up to 930 meters per second . When chambered for 5.7 mm it has a 5 round magazine, and it...
weighs about one third as much as regular ammunition for the same caliber.
While it seems a simple operation to replace the case with a piece of solid propellant, the cartridge case provides more than just a way to keep the cartridge components together, and these other functions must be replaced if the case is to be replaced. Caseless ammunition is not without its drawbacks, and it is these drawbacks that have kept modern caseless ammunition from achieving wider success.
Heat sensitivity
The first major problem, of great concern to the military, is the heat sensitivity of the ammunition. Nitrocellulose, the primary component of modern gunpowderGunpowder
Gunpowder, also known since in the late 19th century as black powder, was the first chemical explosive and the only one known until the mid 1800s. It is a mixture of sulfur, charcoal, and potassium nitrate - with the sulfur and charcoal acting as fuels, while the saltpeter works as an oxidizer...
, ignites at a very low temperature of around 170°C. One of the functions of the metallic cartridge case is as a heat sink
Heat sink
A heat sink is a term for a component or assembly that transfers heat generated within a solid material to a fluid medium, such as air or a liquid. Examples of heat sinks are the heat exchangers used in refrigeration and air conditioning systems and the radiator in a car...
; the metallic case carries away a significant amount of the heat from combustion of the propellant, slowing the rate at which heat is transferred to the chamber. The thermal insulation also works the other way around, shielding the charge from built-up heat from the chamber walls. Without a case to provide these functions, caseless rounds using nitrocellulose will begin to cook off
Cooking off
Cooking off refers to ammunition exploding prematurely due to heat in the surrounding environment. It can also refer to a technique used when throwing grenades to achieve a controlled, predictable explosion....
, firing from the residual chamber heat, much sooner than metal cased cartridges would. The normal solution to the problem of heat is to increase the heat resistance by switching to a propellant with a higher ignition temperature, typically a non-crystalline explosive carefully formulated to provide an appropriate rate of combustion. Heckler & Koch, in concert with Dynamit Nobel, managed such a task by producing relatively heat-resistant caseless ammunition.
Sealing
Another important function provided by the cartridge is to seal the rear of the chamber. During firing of a cased cartridge, the pressure in the chamber expands the brass and blocks the chamber. This prevents gas exiting from the rear of the chamber, and it has also been experimentally shown to provide a significant amount of support to the bolt. Without the case to provide this seal, the firearm design must account for this and provide a means of sealing the rear of the chamber. This problem was also encountered with the Dreyse needle gun; the French ChassepotChassepot
The Chassepot, officially known as Fusil modèle 1866, was a bolt action military breechloading rifle, famous as the arm of the French forces in the Franco-Prussian War of 1870 and 1871. It replaced an assortment of Minie muzzleloading rifles many of which were converted in 1867 to breech loading...
solved the leaking breach problem with the addition of a rubber
Rubber
Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...
seal to the bolt.
Telescoping caseless rounds must also deal with the issue of blocking the bore, as the bullet is surrounded by propellant. The booster charge is used to address this issue, providing an initial burst of pressure to force the bullet out of the cartridge body and into the barrel before the body combusts.
Fragility
Caseless rounds are limited by the fact that the cartridge body is primarily a propellant, and structural properties are secondary to the combustion properties. The primary issue is one of extraction. While caseless ammunition eliminates the need to extract a fired case, unfired cases must be extracted in case of a misfire, or to unload the firearm. In metallic cases, this ability is provided by a rimRim (firearms)
A rim is an external flange that is machined, cast, molded, stamped or pressed around the bottom of a firearms cartridge. The rim may serve a number of purposes, the most common being as the place for the extractor to engage...
or extractor groove machined into the rear of the case. Even in completely plastic
Plastic
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...
bodied cartridges, such as the Activ brand shotgun shell
Shotgun shell
A shotgun shell is a self-contained cartridge loaded with lead shot or shotgun slug designed to be fired from a shotgun....
s, a thin metal ring is molded into the rim to provide support for the extractor.
Modern caseless firearms
One of the first caseless firearm and ammunition systems produced was actually made by DaisyDaisy Outdoor Products
Daisy is a company that makes and sells inexpensive BB guns and other air guns.-History:Daisy was started in 1882 as Plymouth Iron Windmill Company in Plymouth, Michigan. In 1886 the company started to give BB guns with purchases of windmills. The gun was so popular the company started to sell guns...
, the airgun maker, in 1968. The V/L Rifle used a .22 caliber (5.5 mm) low powered caseless round with no primer. The rifle was basically a spring-piston air rifle, but when used with the V/L ammunition the energy from the compression of the piston heated the air behind the caseless cartridge enough to ignite the propellant, and this generated the bulk of the energy of firing. The Daisy V/L
Daisy V/L
The Daisy V/L was the first production rifle for caseless ammunition. It was released in 1968 by Daisy Outdoor Products.The V/L ammunition consisted of a .22 caliber bullet with a small disk of propellant on the back, and no primer...
Rifle system was discontinued in 1969 after the BATF
Bureau of Alcohol, Tobacco, Firearms and Explosives
The Bureau of Alcohol, Tobacco, Firearms and Explosives is a federal law enforcement organization within the United States Department of Justice...
ruled that it was not an airgun, but a firearm, which Daisy was not licensed to produce.
Several assault rifle
Assault rifle
An assault rifle is a selective fire rifle that uses an intermediate cartridge and a detachable magazine. Assault rifles are the standard infantry weapons in most modern armies...
s have used caseless ammunition. One of the better-known weapons of this type is the G11
Heckler & Koch G11
The Heckler & Koch G11 is a non-production prototype assault rifle developed during the late 1960s, 1970s and 1980s by Gesellschaft für Hülsenlose Gewehrsysteme , a conglomeration of companies headed by firearm manufacturer Heckler & Koch , Dynamit Nobel The Heckler & Koch G11 is a non-production...
made by Heckler & Koch
Heckler & Koch
Heckler & Koch GmbH is a German defense manufacturing company that produces various small arms. Some of their products include the SA80, MP5 submachine gun, G3 automatic rifle, the G36 assault rifle, the HK 416, the MP7 personal defense weapon, the USP series of handguns, and the high-precision...
. Although the rifle never entered full production, it went through a number of prototype stages as well as field testing before being put aside in favour of a more conventional firearm, the G36
Heckler & Koch G36
The Heckler & Koch G36 is a 5.56×45mm assault rifle, designed in the early 1990s by Heckler & Koch in Germany as a replacement for the 7.62mm G3 battle rifle. It was accepted into service with the Bundeswehr in 1997, replacing the G3...
, which was also cheaper.
The first commercial caseless rifle featuring electronic firing
Electronic firing
Electronic firing refers to the use of an electric current to fire a cartridge, instead of a percussion cap.In modern firearm designs, a firing pin and percussion cap are used to ignite the propellant in the cartridge and propels the bullet forward...
was the Voere VEC-91
Voere VEC-91
The Voere VEC-91, made by Voere, is the first commercial sporting rifle to combine caseless ammunition and electronic firing. Depending upon its chambering, it fires a 5.7 mm or 6 mm projectile at speeds of up to 930 meters per second . When chambered for 5.7 mm it has a 5 round magazine, and it...
.
In January 1969 the US Army deployed their then new aluminum built M551 Sheridan
M551 Sheridan
The M551 Sheridan was a light tank developed by the United States and named after Civil War General Philip Sheridan. It was designed to be landed by parachute and to swim across rivers. It was armed with the technically advanced but troublesome M81/M81E1 152mm gun/launcher which fired conventional...
tanks to Vietnam
Vietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
. The Sheridan fired combustible-cased ammunition from its 152mm main gun. When the breech was opened after firing, only smoke exited from the chamber.
The Rheinmetall RMK30
Rheinmetall RMK30
The RMK 30 is a recoilless 30 mm caliber autocannon firing caseless 30 x 250 mm ammunition cartridges...
was designed to use 30x250mm
30 mm caliber
30 mm caliber ammunition is usually used in autocannon. Such ammunition includes NATO standard 30 × 173 mm and 30 × 113 mm and Soviet 30 × 165 mm ammunition widely used around the world....
caseless rounds.
See also
- Metal Storm Limited
- H&K G11
- Lightweight Small Arms TechnologiesLightweight Small Arms TechnologiesThe Lightweight Small Arms Technologies program is funded by the U.S. Joint Service Small Arms Program, with the goal of significantly reducing the weight of small arms and their ammunition...
- Polymer-cased ammunitionPolymer-cased ammunition-Overview:A plastic cylinder makes up the body of the cartridge. Starting from the back of the interior of the cartridge: The primer material. A priming method for rimfire cartridges is disclosed in which a propellant solution is disposed adjacent a centrifugally located primer material in a...