Rimfire ammunition
Encyclopedia
Firearm
A firearm is a weapon that launches one, or many, projectile at high velocity through confined burning of a propellant. This subsonic burning process is technically known as deflagration, as opposed to supersonic combustion known as a detonation. In older firearms, the propellant was typically...
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...
. It is called a rimfire because instead of the firing pin
Firing pin
A firing pin or striker is part of the firing mechanism used in a firearm or explosive device e.g. an M14 landmine or bomb fuze. Firing pins may take many forms, though the types used in landmines, bombs, grenade fuzes or other single-use devices generally have a sharpened point...
of a gun striking the primer cap at the center of the base of the cartridge to ignite it (as in a centerfire cartridge
Centerfire ammunition
A centerfire cartridge is a cartridge with a primer located in the center of the cartridge case head. Unlike rimfire cartridges, the primer is a separate and replaceable component....
), the pin strikes the base's rim
Rim (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...
.
The rim of the rimfire cartridge is essentially an extended and widened percussion cap
Percussion cap
The percussion cap, introduced around 1830, was the crucial invention that enabled muzzleloading firearms to fire reliably in any weather.Before this development, firearms used flintlock ignition systems which produced flint-on-steel sparks to ignite a pan of priming powder and thereby fire the...
which contains the priming compound, while the cartridge case itself contains the propellant
Propellant
A propellant is a material that produces pressurized gas that:* can be directed through a nozzle, thereby producing thrust ;...
powder and the projectile (bullet
Bullet
A bullet is a projectile propelled by a firearm, sling, or air gun. Bullets do not normally contain explosives, but damage the intended target by impact and penetration...
).
Once the rim of the cartridge has been struck and the bullet discharged, the cartridge cannot be reloaded, because the head has been deformed by the firing pin impact.
While many other different cartridge priming methods have been tried since the 19th century, only rimfire technology and centerfire technology survive today in significant use.
Characteristics
Rimfire cartridges are limited to low pressure calibers because they require a thin case so that the firing pin can crush the rim and ignite the primer. Although rimfire calibers up to .44 (11 mm) were once common, modern rimfires tend to be of caliber .22 (5.5 mm) or smaller. The low pressures mean that rimfire firearms can be very light and inexpensive, which has helped lead to the continuing popularity of small-caliber Rimfire Cartridges.Economics
Rimfire cartridges are typically inexpensive, primarily due to the inherent cost-efficiency of the ability to make large production quantities (called "lots"). Until 2002, a "brick" of 500 inexpensive .22 Long Rifle.22 Long Rifle
The .22 Long Rifle rimfire cartridge is a long established variety of ammunition, and in terms of units sold is still by far the most common in the world today. The cartridge is often referred to simply as .22 LR and various rifles, pistols, revolvers, and even some smoothbore shotguns have...
cartridges typically cost less than US$10.00. Beginning in 2003, the price of metals used in cartridges (lead, copper and zinc) increased dramatically.
This caused the typical price of a "brick" of .22 long rifle cartridges to increase to US$15.00-$20.00, with single boxes of 50 rounds going for about US$1.75-$2.50 each. Premium or match-grade .22 Long Rifle cartridges, as well as less common or out-of-production rimfire cartridges (such as the .22 Short
.22 Short
.22 Short is a variety of .22 caliber rimfire ammunition. Developed in 1857 for the first Smith and Wesson revolver, the .22 rimfire was the first American metallic cartridge....
, .22 Long
.22 Long
.22 Long is a variety of .22 caliber rimfire ammunition. The .22 Long is the second oldest of the surviving rimfire cartridges, dating back to 1871, when it was loaded with a 29 grain bullet and 5 grains of black powder, 25% more than the .22 Short it was based on...
, .22 Extra Long
.22 Extra Long
The .22 Extra Long is a .22 in American rimfire rifle and handgun cartridge.Introduced around 1880, the .22 Extra Long was used in Remington, Ballard, Wesson, Stevens, and later models of Winchester's M1903 and M1904 single shot bolt action rifles, as well as in Smith & Wesson revolvers.Using the...
, .22 Winchester Auto
.22 Winchester Automatic
The .22 Winchester Automatic is a .22 in American rimfire rifle cartridge....
, and 5 mm Remington Rimfire Magnum
5 mm Remington Rimfire Magnum
The 5 mm Remington Rimfire Magnum is an obsolete bottlenecked rimfire cartridge introduced by Remington Arms Company in 1970. Remington chambered it in a pair of bolt-action rifles, the Model 591 and Model 592, but the round never became very popular, and the rifles were discontinued in 1974....
), can cost substantially more.
History
The idea of placing a priming compound in the rim of the cartridge evolved from an 1831 patent, which called for a thin case, coated all along the inside with priming compound.By 1845, this had evolved into the Flobert .22 BB
.22 BB
.22 BB Cap is a variety of .22 caliber rimfire ammunition. .22 BB cap and .22 CB refer to cartridges that are low velocity and project reduced noise. These rimfires closely resemble a .22 caliber air rifle in power and are often used for indoor shooting and close range pest control...
Cap, which distributed the priming compound just inside the rim. The .22 BB Cap is essentially just a percussion cap with a round ball pressed in the front, and a rim to hold it securely in the chamber. Intended for use in an indoor "gallery" target rifle, it used no gunpowder, but relied entirely on the priming compound for propulsion. Velocities were very low, comparable to an airgun. The next rimfire cartridge was the .22 Short, developed for Smith and Wesson's first revolver
Smith & Wesson Model 1
The Smith & Wesson Model 1 was the first firearm manufactured by Smith & Wesson, with production commencing in 1857. It was also the first commercially available revolver to use rimfire cartridges instead of loose powder, musket ball, and percussion caps...
, in 1857; it used a longer rimfire case and 4 grains (260 mg) of black powder to fire a conical bullet.
This led to the .22 Long, same bullet weight as the short, but with a longer case and 5 grains (320 mg) of black powder. This was followed by the .22 Extra Long with a case longer than the .22 Long and a heavier bullet. The .22 Long Rifle is a .22 Long case loaded with the heavier Extra Long bullet intended for better performance in the long barrel of a rifle
Rifle
A rifle is a firearm designed to be fired from the shoulder, with a barrel that has a helical groove or pattern of grooves cut into the barrel walls. The raised areas of the rifling are called "lands," which make contact with the projectile , imparting spin around an axis corresponding to the...
. The .22 Long Rifle is the most common cartridge in the world. While larger rimfire calibers were made, such as the .41 Rimfire Short
.41 Rimfire Cartridge
The .41 Rimfire Cartridge was first introduced by the National Arms Company in 1863 and was also known as the .41 Short and the .41-100. In most designations like this, the second number refers to the black powder load, though in this case, it is clearly impossible to fit 100 grains of black...
, the .44 Henry Flat
.44 Henry
The .44 Henry, also known as the .44 Rimfire, the .44 Long Rimfire, or the 11x23R cartridge was a rim-fire round that uses a .875 inch casing. The round has a total length of 1.345 inches. It uses a 200 or 216 grain bullet with a .446 diameter. The cartridge was loaded with 26 to 28...
devised for the famous Henry Repeating Rifle
Henry rifle
The Henry repeating rifle was a lever-action, breech-loading, tubular magazine rifle.-History:The original Henry rifle was a .44 caliber rimfire, lever-action, breech-loading rifle designed by Benjamin Tyler Henry in the late 1850s. The Henry rifle was an improved version of the earlier Volcanic...
, up to the .58 Miller, the larger calibers were quickly replaced by centerfire versions, and today the .22 caliber rimfires are all that survive of the early rimfires.
The early 21st century has seen a revival in interest in rimfire cartridges, with two new rimfires introduced, both in .17 caliber (4.5 mm).
Below is a list of the most common current production rimfire ammunition:
- The powderless .22 Cap rounds, including BB Cap.
- .22 Short, used for target shootingPlinkingPlinking refers to informal target shooting done at non-traditional targets such as tin cans, glass bottles, and balloons filled with water. The term is an onomatopoeia of the sound a bullet or other projectile makes when hitting a tin can, or other similar target, referring to the sharp, metallic...
and OlympicOlympic GamesThe Olympic Games is a major international event featuring summer and winter sports, in which thousands of athletes participate in a variety of competitions. The Olympic Games have come to be regarded as the world’s foremost sports competition where more than 200 nations participate...
and ISSF 25 m Rapid Fire Pistol25 m Rapid Fire Pistol25 metre rapid fire pistol is one of the ISSF shooting events. The event has been a part of the Olympic program ever since the beginning in 1896, although its rules changed greatly before World War II, after which they were only slightly changed until the two major revisions of 1989 and 2005...
competition until 2005 - .22 Long (obsolete)
- .22 Long Rifle (.22 LR), the most common cartridge made
- .22 Long Rifle High Velocity Mini-Mag (.22 LR)
- .22 Stinger (slightly longer case, same overall loaded length) - the basis for the .17 HM2.17 HM2The .17 Hornady Mach 2, or .17 HM2, is a rimfire cartridge introduced in 2004 by the ammunition manufacturer Hornady, following the successful launch in 2002 of the .17 HMR...
- .22 Winchester Rimfire (.22 WRF) AKA .22 Remington Special (obsolete)
- .22 Winchester Magnum Rimfire (.22 WMR)
- .17 Hornady Magnum Rimfire (.17 HMR.17 HMR.17 Hornady Magnum Rimfire, commonly known as the .17 HMR, is a rimfire rifle cartridge developed by the ammunition company Hornady in 2002. It descended from the .22 Magnum by necking down the .22 Magnum case to take a .17 caliber bullet, and it is more costly to shoot than traditional .22...
), a .17 caliber based on the .22 WMR case - .17 Hornady Mach 2 (.17 HM2.17 HM2The .17 Hornady Mach 2, or .17 HM2, is a rimfire cartridge introduced in 2004 by the ammunition manufacturer Hornady, following the successful launch in 2002 of the .17 HMR...
), a .17 caliber based on the .22 Stinger case - 5 mm Remington Rimfire Magnum5 mm Remington Rimfire MagnumThe 5 mm Remington Rimfire Magnum is an obsolete bottlenecked rimfire cartridge introduced by Remington Arms Company in 1970. Remington chambered it in a pair of bolt-action rifles, the Model 591 and Model 592, but the round never became very popular, and the rifles were discontinued in 1974....
(recently put back into production by Aguila Ammunition/Centurion)
A new and increasingly popular rimfire, the 17 HMR is basically a .22 WMR with a smaller formed neck which accepts a .17 bullet. The advantages of the 17 HMR over .22 WMR and other rimfires are its much flatter trajectory, and its highly frangible hollow point bullets (often with plastic "ballistic tips" that improve the external ballistics
External ballistics
External ballistics is the part of the science of ballistics that deals with the behaviour of a non-powered projectile in flight. External ballistics is frequently associated with firearms, and deals with the behaviour of the bullet after it exits the barrel and before it hits the target.-Forces...
performance). The .17 HM2 [Hornardy Mach 2] is based on the .22 Long Rifle and offers similar performance advantages over its parent cartridge, at a significantly higher cost. While .17 HM2 sells for about four times the cost of .22 Long Rifle ammunition (per box of 50 rounds), it is still significantly cheaper than most centerfire ammunition, and somewhat cheaper than the .17 HMR.
A notable rimfire still in production in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, and chambered by the Winchester Model 39 in the 1920s, is the 9 mm Flobert. This cartridge can fire a small ball, but is primarily loaded with a small amount of shot, and used in smoothbore
Smoothbore
A smoothbore weapon is one which has a barrel without rifling. Smoothbores range from handheld firearms to powerful tank guns and large artillery mortars.-History of firearms and rifling:...
guns as a miniature shotgun, or "garden gun". Power and range are very limited, making it suitable only for pest control.
Shot
Some ammunition products for the .22 LR fire a small amount of #11 or #12 shot (about 1/15th ounce). The shot is only marginally effective in close ranges, and is usually used for shooting rats or other small animals. It is also useful for shooting birds inside storage buildings as it will not penetrate walls or ceilings. At a distance of about 10 feet (3 m) the pattern is about 8 inches (20 cm) in diameter from a standard rifle, which is about the maximum effective range. Special smoothbore shotguns, such as Marlin'sMarlin Firearms
Marlin Firearms Co., formerly of North Haven, Connecticut, is a manufacturer of high power, center fire, lever action, and .22 caliber rimfire rifles. In the past, the company made shotguns, derringers and revolvers...
Garden Gun
Marlin Model 25MG
The Marlin Model 25MG is a smooth bore, bolt-action, .22 WMR shotgun manufactured by Marlin firearms Company. It was designed and marketed as a "garden gun" for use in dispatching small garden and farm pests. It features a hardwood Monte Carlo stock....
can produce effective patterns out to 15 or 20 yards using .22 WMR shotshells, which hold 1/8 oz. of #11 or #12 shot contained in a plastic capsule.
Shotshells will not feed reliably in some magazine fed firearms, due to the unusual shape of crimped brands, and the relatively fragile plastic tips of other brands. Shotshells will also not produce sufficient power to cycle semiautomatic actions, because, unlike projectile ammunition, nothing forms to the lands and grooves of the barrel to create the pressure necessary to cycle the firearm's action.