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 a .22 LR and various rifles, pistols, revolvers, and even some smoothbore shotguns have been manufactured in this caliber. For many decades, it has been a very popular cartridge around the world. It is one of the few cartridges that are accepted by a large variety of rifles, as well as pistols. Virtually every manufacturer of cartridge firearms makes at least one model chambering it, and this has been true for more than a century. The .22 Long Rifle and related cartridges use a heeled bullet, which means that the bullet is the same diameter of the case, and has a narrower "heel" portion that fits in the case.

The low cost, minimal recoil, and low noise make the .22 LR an ideal cartridge for recreational shooting, and it is often purchased in bulk. The standard box of .22 LR contains 50 rounds, and .22 LR is often sold by the brick, containing 10 boxes for 500 rounds, or the case containing 10 bricks for 5000 rounds.

.22 LR ammunition is available in a very wide variety, and a very wide price range. Bullet weights range from 30 to 60 grains (1.9 to 3.9 g), velocities from 350 to 1750 feet per second (110 to 530 m/s). "Promotional" loads for plinking can be found for under US$10.00 per brick ($0.02 per cartridge), while precision target rounds can cost US$80.00 per brick. Currently, a standard box of 50 rounds goes for $2-3 US. For comparison, a box of 9x19mm, another popular and relatively inexpensive round for semi-automatic handguns, costs closer to $8-10 USD per box of 50. It's common to shoot well over a hundred rounds on a single shooting range visit, and savings add up quickly. For rifle shooting, the price

.22 Long Rifle
.22 Long Rifle - Subsonic Hollowpoint (Left), Standard Velocity (Center), Hyper-Velocity "Stinger" Hollowpoint (Right).
Type	Rimfire cartridge
Place of origin	United States
Specifications
Case type	Rimmed, Straight
Bullet diameter	5.68 mm (0.224 in)
Rim diameter	6.88 mm (0.271 in)
Rim thickness	1.00 mm (0.039 in)
Case length	15 mm (0.591 in)
Overall length	25 mm (0.984 in)

Performance

The .22 LR is effective within 150 meters (490 ft) (after 150 meters the ballistics of the round are such that the large "drop" will be difficult to compensate). The relatively short effective range, low report, and light recoil has 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. Still, the effectiveness of this cartridge is often underestimated. The trajectory of the .22 LR "has a 2.7 inch rise at 50 yards and 10.8 inch drop at 150 yards when zeroed at 100 yards."^[1] "Practically speaking, a .22 LR rifle needs to be zeroed at about 75 yards to avoid over-shooting small animals like squirrels at intermediate distances." ^[2]

The newest commercial rimfire, the .17 Mach 2, is based on the .22 LR case, but is slightly stretched in length (case length is similar to the CCI Stinger) and necked down. The light, aerodynamic .17 caliber (4.5 mm) bullet gives a much higher velocity than the .22 LR, for similar energy and a much flatter trajectory, but at the expense of increased cost and noise.

As a hunting cartridge, the .22 LR is mainly used to kill small vermin such as rats and squirrels. It is also highly effective on rabbits at distances closer than 150 yards and on ground hogs, marmots, and foxes closer than 80 yards. It has been successfully used on large creatures such as coyotes, but range should be limited to no farther than 65 yards, head and chest shots are mandatory with the most powerful .22 cartridge the hunter can use accurately. The hunter would best find what cartridge out of the various high velocity and hyper velocity shoots well for him by preliminary testing. For greater range or larger game, a more powerful cartridge should be used to ensure a clean kill. Examples include larger rimfire rounds such as the .22 WMR, .17 HMR, or any centerfire cartridge. Like any bullet, the .22 LR is nonetheless dangerous and capable of killing humans and large animals at close range.

Variants

There are a variety of different types of .22 Long Rifle (or ".22 LR") loads. They are often divided into 4 distinct categories:

• subsonic velocity (also includes "target" or "match" loads at velocities below 1100 feet per second nominal velocity)
• standard velocity (1120 -1135 feet per second nominal velocity)
• high velocity (1200-1310 feet per second nominal velocity)
• hyper-velocity (also known as ultra-velocity with speeds over 1400 feet per second nominal velocity)

Subsonic rounds have a muzzle velocity of 330 m/s (1082 ft/s) or less and are sometimes equipped with an extra heavy, 46-61 grain (2.9-3.9 gram) bullet. Conversely, some rounds contain little more than primer and an extra-light bullet. Subsonic rounds are especially favored for their perceived improved target accuracy, and for hunting. This is because when the bullet breaks the sound barrior, its accuracy suffers. As the speed of sound in air at 68 °F (20 °C)is approximately 1126 ft/s (343.4 m/s), the subsonic round's muzzle velocity is close to the speed of sound under many hunting conditions, or only very slightly below it. However, under cold air conditions at 32 °F (0 °C), the speed of sound drops to 331.5 m/s (1087.6 ft/s), essentially the same speed as the muzzle velocity of the subsonic round. Hence, a so-called subsonic round when used under slightly colder conditions than 0 °C (32 °F) is often no longer subsonic and instability may arise when crossing down through the speed of sound, reducing accuracy. To counteract this, some cartridge manufacturers have lowered the speed of their subsonic ammunition to 1030 ft/s (315 m/s)or significantly less, while other manufacturers still sell subsonic ammunition with a velocity only slightly under 1082 ft/s (330 m/s. Subsonic rounds do not work well in all semi-automatic .22 LR firearms, often failing to cycle the action.

Standard velocity rounds have a slightly supersonic muzzle velocity of around 1125 ft/s(350 m/s) and a "normal" bullet weight of 40 grains (2.5 grams). Standard velocity cartridges generate near or slightly-supersonic velocities. These rounds generally do not develop these velocities in handguns because the short barrel does not take full advantage of the slower powder. The downside to supersonic rounds is that the bullet often drops to subsonic speeds on its way to the target which can degrade accuracy. The extra power and penetration, however, more than make up for the slight loss in accuracy for applications such as small game hunting.

Many .22 LR cartridges use bullets lighter than the standard 40 grains (2.6 g), fired at even higher velocities. The CCI Stinger was the first "hyper velocity" .22 LR cartridge, and provides a significant increase in velocity over standard .22 LR rounds. The Stinger uses a longer case, a stronger charge and copper plating on a lighter bullet. The case is longer than that of the normal Long Rifle cartridge, yet Stingers will fit in most Long Rifle chambered firearms. The powder is designed to burn more slowly and thus make the most use of the length of a rifle barrel. In the Stinger the extra case length is compensated by a shorter bullet, which is only available as a plated hollow point. The thin copper layer on the bullet functions as a lubricant and reduces the friction between the high velocity bullet and the barrel, thus reducing barrel wear. It also has an oxidation-preventing effect on the lead bullet. Lead tends to oxidise if stored over long periods of time and as a result of this, the bullet's diameter increases to a level that might both prevent the insertion of the cartridge in the chamber and might cause the pressure in the barrel to rise to a dangerously high level. The increase in pressure may lead to the case rupturing and potential danger to the shooter. Standard and subsonic cartridges tend to use a type of wax for the same purpose.

Hyper-velocity bullets can have a muzzle velocity of 425 to 550 m/s (1400-1804 ft/s)and this velocity is partially because of the light bullets they use. The bullets are usually around 30 grains (1.9-2.2 grams) in weight. However there is a round that is classified as "hypervelocity" that utilizes a 40 grain (2.6g) projectile. This cartridge, called the Velocitor is manufactured by CCI, owned by Alliant Corporation, it has a muzzle velocity of 1,435 ft/s (450 m/s). This cartridge utilizes a conventional case size, as opposed to the longer case used by a stinger. The Velocitor uses a proprietary Gold Dot hollow Point to augment expansion and trauma when hunting, this special hollow point is used to keep the bullet's full 40 grains. Whereas in many other hunting cartridges weight is reduced to make a hollowed out point, or a hollow point.

Special shot cartridges, called rat-shot, usually loaded with #12 shot (see shotgun shell) in a .22 LR caliber have also been made and these are ideal for pest control at very short ranges. Such rounds will either have a longer brass case that is crimped closed, or a translucent plastic "bullet" that contains the shot and shatters upon firing. In specially-made .22 bore shotguns, the shotshells can be used for short range skeet shooting and trap shooting at special, scaled-down, clay targets.

During WW II, a full metal jacketed version of the 22 LR was developed for the suppressed High Standard HDM pistol to counter concerns of the legality of using hollowpoint 22 LR bullets in wartime.

Usage

Today .22 Long Rifle ammunition is mainly being used for hunting small pests, for sports shooting, for plinking, and for cheap training. The .22 LR is the choice for several ISSF shooting events: 50 m Rifle, 50 m Pistol, 25 m Pistol, 25 m Rapid Fire Pistol and 25 m Standard Pistol, Bullseye (shooting competition), plus divisions of metallic silhouette and pin shooting, most high school, collegiate, Boy Scouts of America, Air Training Corps, and 4H shooting events, and many others. With high quality ammunition, the .22 Long Rifle can be quite accurate. Its main advantages are low cost, low recoil, low noise and high accuracy to cost ratio. Its main disadvantage is its low power; it is only suitable for use on small game and other small animals^[3] and as a defensive cartridge it is considered inadequate, 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, 22 LR pistols and rifles can be lethal and are often used for self defense simply because they are prevalent, inexpensive, and widely available to civilians.

Semi-automatic rifles firing .22 Long Rifle cartridges often will work properly only when firing high velocity .22 LR ammunition; subsonic rounds will often not cycle their actions properly. Bolt-action or lever-action rifles, however, can utilize any of the variants (high velocity to subsonic.)

The tiny case of the 22 Long Rifle and the subsonic velocities (when using subsonic ammunition) make it well suited for use with a firearm silencer. The low volume of powder gasses mean that 22 LR silencers 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 silencers are only minimally restricted, a 22 Long Rifle firearm with a silencer is often favored for plinking, as it does not require hearing protection or disturb the neighbors. Local government agencies sometimes use suppressed 22 LR weapons for animal control, since dangerous animals or pests can be dispatched in populated areas without causing undue alarm.

Intelligence agencies and military special forces have used suppressed 22 LR pistols for assassinations and for eliminating guard dogs or sentries. Some examples include the use of suppressed High Standard HDM pistols by the American OSS, which was the predecessor organization of the CIA. Gary Powers was issued a suppressed High Standard for the flight in which he was shot down. Suppressed Ruger MK II pistols are in current use by the US Navy SEALs.

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. One weapon designed for this purpose is the Russian SV-99 rifle.

Specifications

Standard dimensions are as follows:

• Case length: 15 mm (0.595 in )
• Case diameter: 5.71 mm (.225 in)
• Bullet diameter: 5.68 mm (.224 in)
• Rim diameter: 6.88 mm (.271 in)
• Rim thickness: 1 mm (.040 in)
• Cartridge overall length: 25 mm (.985 in)