History
American firearms manufacturer J. Stevens Arms & Tool Company introduced the .22 Long Rifle cartridge in 1887. The round owes its origin to the .22 BB Cap of 1845 and the .22 Short of 1857. It combined the case of the .22 Long of 1871 with a bullet, giving it a longer overall length, a higher muzzle velocity and superior performance as a hunting and target round, rendering the .22 Extra Long cartridges obsolete. The .22 LR uses a heeled bullet, which means that the bullet is the same diameter as the case, and has a narrower "heel" portion that fits in the case. It is one of the few cartridges that are accepted by a large variety of rifles and handguns.Popularity
The .22 LR cartridge is popular with both novice shooters and experts. Its minimal recoil and relatively low noise make it an ideal cartridge for recreational shooting, small-game hunting, and pest control. .22 LR cadet rifles are commonly used by military cadets and others for basic firearms and marksmanship training. It is used by the Boy Scouts of America for the rifle shooting merit badge. The low recoil of the cartridge makes it ideal for introductory firearms courses. Novice shooters can be surprised or frightened by the noise and recoil of more powerful rounds. Beginners shooting firearms beyond their comfort level frequently develop a habit of flinching in an attempt to counter anticipated recoil. The resulting habit impedes correct posture and follow-through at the most critical phase of the shot and is difficult to correct. With high recoil eliminated, other errors in marksmanship technique are easier to identify and correct. Available for this round arePerformance
Two .22 LR rounds compared to a cartridge">.45 ACP cartridge The .22 LR is effective to , though practical ranges tend to be less. After 150 yd, the ballistics of the round are such that it will be difficult to compensate for the large "drop". The relatively short effective range, low report, and light recoil have made it a favorite for use as a target-practice cartridge. The accuracy of the cartridge is good, but not exceptional; various cartridges are capable of the same or better accuracy. A contributing factor in rifles is the transition of even a high-velocity cartridge projectile fromVariants
The variety of .22 LR loads are often divided into four distinct categories, based on nominal velocity: * Subsonic, which also includes "target" or "match" loads, at nominal speeds below . * Standard-velocity: * High-velocity: * Hyper-velocity, or Ultra-velocity: overSubsonic
Subsonic rounds have a muzzle velocity of less than the speed of sound (about ). These rounds are sometimes equipped with extra-heavy bullets of to improve the terminal ballistics of the slower projectile. Conversely, these rounds may contain little more than a primer and an extra-light bullet. Subsonic rounds are favored by some shooters due to slightly superior accuracy and reduction in noise. Supersonic rounds produce a loud crack which can scare away animals when hunting. Accuracy is reportedly improved with subsonic rounds because a supersonic bullet (or projectile) that slows from supersonic to subsonic speed undergoes drastic aerodynamic changes in this transonic zone that might adversely affect the stability and accuracy of the bullet. Because the speed of sound in air at is about , the subsonic round's muzzle velocity is slightly below the speed of sound under many hunting conditions. However, under cold air conditions at , the speed of sound drops to , approximately muzzle velocity. Hence, a "subsonic" round used below this temperature may be supersonic, and during the transition from supersonic to subsonic velocity, it may become unstable, reducing accuracy. To counteract this, some cartridge manufacturers have lowered the speed of their subsonic ammunition to or less. Various combinations of subsonic rounds and semiautomatic .22 LR firearms result in unreliable cycling of the firearms' actions, as the result of insufficient recoil energy. Some subsonic rounds use heavier bullets (achieving lower velocities) to ensure, as a result of increased bullet mass, that enough energy is produced to cycle common blow-back actions. As an example, the Aguila .22 LR SSS "Sniper SubSonic" round, has a bullet on a .22 short case, providing the cartridge the same overall dimensions as a .22 long rifle round. However, other problems may be encountered: the heavier and longer bullet of the Aguila cartridge requires a faster barrel twist (by the Greenhill formula) to ensure the bullet remains stable in flight. Two performance classes of .22 rimfire subsonic rounds exist. Some subsonic rounds, such as various .22 short and .22 long "CB" rounds, give about velocity with a bullet providing relatively low impact energy (41 J at muzzle). These may not use any, or only small amounts of gunpowder, and have the characteristics of rounds intended only for indoor training or target practice rather than hunting. Where these are in .22 LR form, it is only to aid feeding in firearms designed for the cartridge, rather than older .22 CB shooting gallery rifles. The Aguila SSS gives about velocity with a 60-gr bullet offering energy (163 Joules) equivalent to many high velocity .22 long rifle rounds using standard 40-gr bullets. Other heavy-bullet subsonic rounds give similar performance, and are intended for hunting of small game, or control of dangerous animals, while avoiding excessive noise.Standard velocity
The velocity of standard-velocity .22 LR rounds varies between manufacturers. Some standard velocity ammo may be slightly supersonic-around , other ammo such as CCI Standard Velocity .22 LR ammunition is rated at . Most standard velocity ammo has a bullet weight of . Standard-velocity cartridges generate near or slightly supersonic velocities. These rounds generally do not develop these velocities in handguns because their short barrels do not take full advantage of the slower burning powder.High velocity
The .22 long rifle round was originally loaded with black powder. The first smokeless powder loads were intended to match the standard velocity of the original black-powder rounds. Smokeless powder is more efficient than black powder, and the cartridge cases could hold more powder. Smokeless powder loads, called "high speed" or "high velocity", were offered by the major ammunition makers, giving a typical velocity increase of 8% ( to ) while still using the standard solid or hollow-point lead bullet.Hyper-velocity
Many .22 LR cartridges use bullets lighter than the standard , fired at even higher velocities. Hyper-velocity bullets usually weigh around and can have a muzzle velocity of . This higher velocity is partially due to the use of lighter bullets. The CCI Stinger was the first hyper-velocity .22 LR cartridge, and provided a significant increase in velocity and energy over standard rimfire rounds. The Stinger case is longer than that of the long rifle; about ''versus'' for the long rifle, but the plated hollow point bullet is lighter and shorter at , giving the same overall length as the long rifle cartridge. This longer case can cause ejection problems in some guns. A powder with a slower burning rate is used to make the most use of the length of a rifle barrel. Most .22 long rifle powders increase velocity up to about of barrel. The powder used in the Stinger increases velocity up to the longest .22 barrel length tested by the NRA, . Later hyper-velocity rounds were introduced by other makers, based on the long rifle case with lighter bullets in the 30-gr weight range and slow-burning rifle powder loadings. The overall length of many of these cartridges was less than the overall length of the standard 40-gr bullet long rifle cartridge. One example is the Remington Viper; another is the Federal Spitfire. The CCI Velocitor hyper-velocity round uses the standard long rifle case size and a standard weight bullet of proprietary hollow-point design to augment expansion and trauma. This cartridge has a muzzle velocity of and matches the overall length of the standard long rifle cartridge.Shot cartridges
Special .22 LR caliber shot cartridges, usually loaded with No. 12 shot, have also been made. These are often called " snake shot," "bird shot" and "rat-shot" due to their use in very short rangeFull metal jacket
During World War II, a full metal jacket bullet version of the .22 LR was developed as the T-42 for the suppressed High Standard HDM pistol. The US Army Air Corps procured the Savage Model 24 .22 LR/.410 combination gun as an air crew survival weapon included in the E series of survival and sustenance kits, primarily to forage for game for food. The .22 LR full metal jacket bullet ammunition was issued with these firearms for military use to comply with treaty restrictions on expanding bullets. The 1961 Army/Air Force Technical Manual/Order on ammunition lists three types of rimfire CARTRIDGE, CALIBER .22: Ball, Long Rifle: *Long Rifle (Lead Bullet), propellant: 1.7 gr smokeless, bullet: 40 gr, overall length: . *Long Rifle (Commercial), propellant: 2.1 gr smokeless, bullet: 40 gr, overall length: about . *Long Rifle, M24 (Jacketed Bullet), propellant: 2.5 gr smokeless, bullet: 40.5 gr, overall length: . The first type specifies standard or target velocity .22 LR while the second is common high velocity commercial ammo. While these soft lead round nose bullet types were suitable for training or target practice, they are not legal for use in a war zone. Since .22 LR air crew survival weapons would probably be used in a war zone and could be used for defense, the M24 round is loaded with a hard lead-antimony alloy core bullet with a gilding metal jacket.Tracer
Tracer ammunition is also available in rimfire.Cartridge construction
The traditional .22 rimfire cartridges (BB, CB, short, long, extra long, and long rifle) differ in construction from more modern cartridges in the way the bullet is constructed and held in the case. Bullets for traditional .22 rimfires are the same outside diameter as the case but are constructed with a narrower cupped " heel" on the base of the bullet which is inserted into the case. The case mouth is then crimped around the heel, leaving exposed the majority of the bullet bearing surface that contacts the barrel of the gun. The bearing surface of .22 rimfire bullets is often lubricated and the surface is exposed to contamination. This was a common design in the early black powder cartridge era. In later cartridges including the .22 WRF and .22 WMR rimfires and modern centerfires, the bullet body is a uniform diameter and the bearing surface is inserted completely within the neck of the cartridge case, held in place by tension from the case neck around the bullet bearing surface (in some cartridges the case mouth may also be crimped into a cannelure (groove) in the bullet). The heeled bullet cartridge is considered weaker than the uniform diameter bullet cartridge which encloses the bearing surface of the bullet within the cartridge neck. Overall reliability of heeled bullet rimfire ammunition is high, but it is lower than the reliability of most centerfire ammunition.Cartridge length
The .22 LR uses a straight-walled case. Depending upon the type and the feed mechanism employed, a firearm that is chambered for .22 LR may also be able to safely chamber and fire the following shorter rimfire cartridges: * .22 BB, in cap, short, and long lengths * .22 CB, in cap, short, long, and long rifle lengths * .22 Short * .22 Long The .22 Long Rifle may also be used in firearms chambered for the obsolete .22 Extra Long.Usage
Today, rimfire rounds are mainly used for hunting small pests, for sports shooting, for plinking, and for inexpensive training. The .22 LR is the choice for several shooting events: biathlon, bullseye, plus divisions of benchrest shooting, metallic silhouette and pin shooting, most high school, collegiate, Boy Scouts of America, Project Appleseed, 4H shooting events, and many others. It is also used in the precision Rifle and Pistol shooting events at the Olympic Games. Good quality rimfire ammunition can be quite accurate. The main advantages are low cost, low recoil, low noise and high accuracy-to-cost ratio. The main disadvantage is its low power; it is better suited for use on small game and other small animals. As a defensive cartridge, it is considered inadequate by many, though the small size allows very lightweight, easily concealable handguns which can be carried in circumstances where anything larger would be impractical. Despite their limitations, people can use .22 LR pistols and rifles for defense, and are common simply because they are prevalent, inexpensive, and widely available. Most semi-automatic rifles firing .22 LR cartridges will often only work properly when firing standard or high velocity rimfire ammunition, as the low recoil of subsonic rounds is insufficient to cycle the weapon's action. Rifles with manual actions do not have this problem. Due to the low bolt thrust of the .22 LR cartridge, most self-loading firearms chambered for the cartridge use the direct blowback operation system. The tiny case of the .22 LR and the subsonic velocities (when using subsonic ammunition) make it well suited for use with a firearm suppressor (also known as silencers or sound moderators). The low volume of powder gases means that .22 LR suppressors are often no larger than a bull barrel; the Ruger 10/22 and Ruger MK II are common choices, because of their reliability and low cost, and the resulting product is often nearly indistinguishable from a bull barrel model (although weighing far less). Where firearm suppressors are only minimally restricted, a .22 LR firearm with a suppressor is often favored for plinking, as it does not require hearing protection or disturb the neighbors. Local government agencies sometimes use suppressed rimfire weapons for animal control, since dangerous animals or pests can be dispatched in populated areas without causing undue alarm. The .22 LR has also seen limited usage by police and military snipers. Its main advantage in this role is its low noise, but it is usually limited to urban operations because of its short range. The Israeli military used a suppressed .22 LR rifle in the 1990s forCartridge dimensions
.22 long rifle maximum C.I.P. cartridge dimensions. All sizes in millimetres (mm). The commonMuzzle velocity (nominal)
* lead: .22 LR subsonic * copper plated lead: .22 LR high velocity * copper plated lead: .22 LR hyper-velocity CCI Stinger Note: actual velocities are dependent on many factors, such as barrel length of a given firearm and manufacturer of a given batch of ammunition, and will vary widely in practice. The above velocities are typical.See also
* .22 BB * .22 CB * .22 Short * .22 Long * .22 Extra Long * .22 Magnum * .22 Hornet * .25 ACP * .220 Rook * 5 mm caliber * .17 HM2 * Cadet rifle * List of rimfire cartridges * Table of handgun and rifle cartridgesReferences
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