The .22 long rifle (.22LR), also known as the 5.7×15mmR, is a long-established variety of .22 caliber rimfire ammunition originating from the United States. It is used in a wide range of firearms, including rifles, pistols, revolvers, and submachine guns. It is a well-established small-game round but is not typically used for hunting larger game, as it lacks the necessary stopping power.
In terms of quantities sold, the .22 Long Rifle is by far the most common ammunition that is currently manufactured and sold in the world. Common uses include hunting and shooting sports. Ammunition produced in .22 Long Rifle is effective at short ranges, has little recoil, and is inexpensive to purchase, making it ideal for plinking and marksmanship training.
History American cartridge manufacturer J. Stevens Arms & Tool Company introduced the .22 long rifle cartridge in 1887.Massaro, P. (2022, September 20). The .22 long rifle – 100-plus years and still going strong. NSSF Let's Go Hunting. https://www.letsgohunting.org/resources/articles/small-game/the-22-long-rifle-100-plus-years-and-still-going-strong/ 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 .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 inside the case. It is one of the few cartridges accepted by a wide 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. Military cadets and others commonly use .22 LR cadet rifles for basic firearms and marksmanship training. The Boy Scouts of America use it for the rifle shooting merit badge.
The cartridge's low recoil 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.
Many handgun manufacturers offer an upper pistol conversion kit to allow the pistol to shoot .22 LR ammunition. These conversions allow shooters to practice inexpensively while retaining the handling characteristics of their chosen firearms (with reduced recoil and muzzle blast). Additionally, .22 LR cartridge conversion kits allow practice at indoor ranges which prohibit high-power firearms. Owners of guns that use gas systems, such as AR-15 sport style rifles, normally avoid firing non-plated .22 LR cartridge ammunition, as the use of non-plated ammunition may cause lead fouling of the gas port inside the barrel and costly gunsmithing procedures. This can usually be mitigated by swapping the conversion kit for the standard bolt carrier group and firing several full-powered rounds to clear the gas port and tube of any accumulated lead fouling. While not 100% effective, the extremely hot, incandescent gases produced by centerfire rifle ammunition will help clear any lead fouling from .22 LR ammunition.
A wide variety of .22 LR ammunition is commercially available, and it varies widely in price and performance. Bullet weights among commercially available ammunition range from , and velocities vary from . .22 LR is the least costly firearm cartridge ammunition available around the world. Promotional loads for plinking can be purchased in bulk for significantly less cost than precision target rounds. The low cost of ammunition has a substantial effect on the popularity of the .22 LR. For this reason, rimfire cartridges are commonly used for target practice.
.22 LR cartridges are commonly packaged in boxes of 50 or 100 rounds, and are often sold by the 'brick', a carton containing either 10 boxes of 50 rounds or loose cartridges totaling 500 rounds, or the 'case' containing 10 bricks totaling 5,000 rounds. Annual production is estimated at 2–2.5 billion rounds by some. The NSSF estimates that a large percentage of the US production of 10 billion cartridges is composed of .22 LR. Despite the high production figures there have occasionally been shortages of .22 LR cartridge in the contiguous United States, most notably during the U.S. ammunition shortage of the late 2000s and early 2010s.
Performance
The .22 LR is effective to , though practical ranges tend to be less. After , 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 cartridge's accuracy is good but not exceptional; other cartridges can achieve the same or better accuracy. A contributing factor in rifles is the transition of even a high-velocity cartridge projectile from supersonic to subsonic within . As the bullet slows, the shock wave generated by supersonic travel overtakes it, disrupting its flight path and causing minor but measurable inaccuracies.
When zeroed for , the arc-trajectory of the standard high-velocity .22 LR with a bullet has a rise at , and a drop at . A .22 LR rifle needs to be zeroed for to avoid overshooting small animals like squirrels and rabbits at intermediate distances.
As a hunting cartridge, rimfires are mainly used to kill small game animals up to the size of coyotes. Although proper shot placement can kill larger animals such as deer or hog, it is not recommended because its low power may not guarantee a humane kill. In 2013, an elephant was killed by multiple shots from a .22 LR rifle.
Because a .22 LR bullet is smaller and less powerful than most larger cartridges, its danger to humans is often underestimated. However, a .22 LR bullet is easily capable of killing or injuring humans. Even after flying , a .22 bullet is still traveling at about . Ricochets are more common in .22 LR projectiles than for more powerful cartridges as the combination of unjacketed lead and moderate velocities allows the projectile to deflectnot penetrate or disintegratewhen hitting hard objects at a glancing angle. A .22 LR bullet can ricochet off the surface of water at a low angle of aim. Severe injury may result to a person or object in the line of fire on the opposite shore, several hundred yards or meters away. A .22 LR bullet is capable of traveling , which is more than .
Rimfire bullets are generally either plain lead with a wax coating (for subsonic-velocity or standard-velocity loads) or plated with copper or gilding metal (for high-velocity or hyper-velocity loads). The thin copper layer on a plated bullet functions as a lubricant, reducing friction between the bullet and the barrel and thus reducing barrel wear. Plating also prevents oxidation of the lead bullet. Lead tends to oxidize if stored for long periods. On a plain lead bullet, oxide on the bullet's surface can increase its diameter enough to either prevent insertion of the cartridge into the chamber, or – with high velocity rounds – cause dangerously high pressures in the barrel, potentially rupturing the cartridge case and injuring the shooter; for that reason, standard and subsonic cartridges usually use a wax lubricant on lead bullets.
Variants The variety of .22 LR loads is often divided into four distinct categories, based on nominal velocity: Subsonic-velocity: and under Standard-velocity: High-velocity: Hyper-velocity/Ultra-velocity: and over
Subsonic-velocity
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.
Some shooters favor subsonic rounds for slightly improved accuracy and reduced 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 action cycling due to 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 blowback actions. As an example, the Aguila .22 LR SSS (sniper sub-sonic) 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, longer bullet of the Aguila cartridge requires a faster barrel twist (as determined 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 at the 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 has a velocity of using a bullet with of energy, which is equivalent to many high velocity .22 long rifle rounds using standard bullets. Other heavy-bullet subsonic rounds perform similarly and are intended for hunting small game or controlling 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/Ultra-velocity