Thursday, January 20, 2011

.22 Long Rifle



.22 Long Rifle

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.22 Long rifle
.22 LR.jpg
.22 Long Rifle – Subsonic Hollow point (left). Standard Velocity (center), Hyper-Velocity "Stinger" Hollow point (right).
Type Rimfire cartridge
Place of origin  United States
Production history
Designer J. Stevens Arm & Tool Company
Designed 1887
Specifications
Case type Rimmed, Straight
Bullet diameter .223 in (5.7 mm)
Neck diameter .225 in (5.7 mm)
Base diameter .225 in (5.7 mm)
Rim diameter .275 in (7.0 mm)
Rim thickness .040 in (1.0 mm)
Case length .590 in (15.0 mm)
Overall length .985 in (25.0 mm)
Rifling twist 1-16
Primer type Rimfire
Ballistic performance
Bullet weight/type Velocity Energy
40 gr (2.6 g) Solid[1] 1,080 ft/s (330 m/s) 104 ft·lbf (141 J)
38 gr (2.5 g) Copper-plated HP[1] 1,260 ft/s (380 m/s) 134 ft·lbf (182 J)
31 gr (2.0 g) Copper-plated HP[1] 1,430 ft/s (440 m/s) 141 ft·lbf (191 J)
30 gr (1.9 g) Copper-Plated RN[2] 1,750 ft/s (530 m/s) 204 ft·lbf (277 J)
32 gr (2.1 g) Copper-Plated HP[2] 1,640 ft/s (500 m/s) 191 ft·lbf (259 J)
Source(s): [1][2]
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 been manufactured in this caliber. It is occasionally referred to by its metric designation of 5.6x15mmR. The cartridge originated from the Flobert BB Cap of 1845 through the .22 Smith & Wesson cartridge of 1857, and was developed by the J. Stevens Arms & Tool Company in 1887[3] by combining the casing of the .22 Long with the 40-grain (2.6 g) bullet of the .22 Extra Long. 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 (.22 Short, .22 Long and .22 Extra Long) use 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.

Popularity

The low cost, minimal recoil, and relatively low noise make the .22 LR an ideal cartridge for recreational shooting, initial firearms training, and pest control, and it is often purchased in bulk. The round is popular among novice shooters and experts alike. .22 LR is commonly packaged in boxes of either 100 or 50 rounds, and is often sold by the brick, a carton containing either 10 boxes of 50 rounds or loose cartridges totalling 500 rounds, or the case containing 10 cartons totalling 5,000 rounds.
.22 LR ammunition is available in a very wide variety, and a very wide price range. Bullet weights range from 20 to 60 grains (1.3 to 3.9 g), velocities from 575 to 1,750 ft/s (175 to 530 m/s). "Promotional" loads for plinking can be found for under US$20.00 per brick ($0.04 per cartridge), while precision target rounds can cost US$80.00 to upwards of US$250.00 per brick. As of June 2010, a box of 50 standard quality FMJ rounds goes for US$3–5. For comparison, a box of similar quality FMJ 9x19 mm Parabellum, another popular and relatively inexpensive round for semi-automatic handguns, costs around US$15 per box of 50. It is common to shoot well over a hundred rounds on a single shooting range visit. For rifle shooting, the price difference is even more dramatic as powerful rifle cartridges like .308 Winchester and .30-06 Springfield can approach and exceed US$1 per cartridge. For this reason especially, .22 LR is commonly used by hunters for off-season target practice. They are also the ammunition used by Boy Scouts for the rifle shooting merit badge.
The low recoil of a .22 LR cartridge makes it ideal for introductory firearms courses. Due to their lack of shooting experience, most novice shooters are surprised and frightened by the recoil of handguns and rifles chambered even for rounds considered mild by experienced shooters. Starting with calibers above the shooter's comfort level frequently leads to the beginner developing a habit of flinching in an attempt to counter the anticipated recoil and ruining the correct posture and follow-through at the most critical phase of the shot. This habit is difficult to undo after it is developed. With the high recoil out of the picture, any other errors in marksmanship technique are easier to identify and correct than they would be on the more powerful guns.
AR-15 upper receivers and M1911 slide assemblies are available for this round. CZ Model 75 handguns also have a fixed barrel upper pistol conversion kit to make it shoot .22 ammunition. These ".22 conversions" allow shooters inexpensive practice while retaining the handling characteristics of their chosen firearms (minus the recoil and muzzle blast). Additionally, .22 kits allow practice at indoor ranges which often prohibit high-power rifles. The 'fun factor' from shooting a high powered pistol or rifle with low energy bullets when converted to .22 is another reason for the conversion kits as well as the much lower costs for practice ammunition. Owners of guns that use gas systems, such as converted AR-15 style rifles, normally avoid firing unjacketed .22LR ammunition. Unless the bullet is covered with a copper jacket, the lead from the bullets will eventually clog the gas port inside the barrel and require extensive gunsmithing to clear out.
Annual production is estimated at 2–2.5 billion rounds.[4][5]

Performance

Two .22 LR rounds compared to a .45 ACP cartridge.
.22 LR is effective to 150 yards (140 m), though practical range tends to be less. After 150 yards 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. A contributing factor in rifles is the transition of even a high-velocity cartridge projectile from supersonic to subsonic within 100 yards (91 m). As the bullet slows, the shock wave caused by supersonic travel overtakes the bullet and can disrupt its flight path, causing minor but measurable inaccuracy.[citation needed]
When zeroed for 100 yards (91 m), the trajectory of the standard high-velocity .22 LR with a 40-grain (2.6 g) bullet has a 2.7-inch (69 mm) rise at 50 yards (46 m), and 10.8 inches (270 mm) drop at 150 yards (140 m).[6] A .22 LR rifle needs to be zeroed for 75 yards (69 m) to avoid over-shooting small animals like squirrels at intermediate distances.[6]
As a hunting cartridge, the .22 LR is mainly used to kill small game such as rats and squirrels. It is also highly effective on rabbits at distances closer than 150 yards (140 m) and on ground hogs, marmots, and foxes closer than 80 yards (73 m). It has been successfully used on large creatures such as coyotes, but range should be limited to no farther than 65 yards (59 m); head and chest shots are mandatory with the most powerful .22 cartridge the hunter can use accurately.
A .22 LR bullet is far less powerful than larger cartridges, but dangerous nonetheless; in fact its deceptive "low-power" reputation can make it more dangerous because some shooters do not pay it the same respect as larger cartridges, and shoot it carelessly. It can easily kill or severely injure humans and large animals.[7][8] Even after flying 400 yards (370 m), a stray .22 bullet is still traveling at approximately 500 ft/s (150 m/s), which can inflict a very serious wound, and a standard .22 cartridge can have a ballistic range of up to a 1.5 miles (2,400 m).[citation needed] 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 deflect - not penetrate or disintegrate - when hitting hard objects at a glancing angle.[citation needed]
.22 Long Rifle bullets are generally either plain lead (for standard velocity loads) or plated with copper or gilding metal (for high velocity or hyper velocity loads). The thin copper layer on the bullet functions as a high velocity lubricant reducing friction between the bullet and the barrel, thus reducing barrel wear. It also prevents oxidation of the lead bullet. Lead tends to oxidize if stored for long periods. Oxide on the bullet's surface could increase its diameter enough to either prevent insertion of the cartridge into the chamber, or - with hyper velocity rounds - cause dangerously high pressures in the barrel, potentially rupturing the cartridge case and injuring the shooter. Standard and subsonic cartridges use a wax lubricant on lead bullets for the same purpose at lower velocities.

Variants

There are a variety of different types of .22 LR loads. They are often divided into four distinct categories, based on nominal velocity:
  • Subsonic, which also includes "target" or "match" loads, at nominal speeds below 1,100 ft/s (340 m/s).
  • Standard-velocity: 1,000–1,135 ft/s (300–346 m/s). Common velocities are around 1,125 ft/s (343 m/s).
  • High-velocity: 1,200–1,310 ft/s (370–400 m/s) per second.
  • Hyper-velocity, or Ultra-velocity: over 1,400 ft/s (430 m/s).

Subsonic
The subsonic .22 CB Long (no gunpowder).
See also: The transonic problem
Subsonic rounds have a muzzle velocity less than the speed of sound (approximately 1,080 ft/s (330 m/s)). These rounds are sometimes equipped with extra heavy bullets of 46–61-grain (3.0–4.0 g) 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. Additionally, the use of subsonic rounds is reported to reduce wastage of meat caused by a high-velocity round passing and destroying tissue.[citation needed]
Because the speed of sound in air at 68 °F (20 °C) is approximately 1,126 ft/s (343 m/s), the subsonic round's muzzle velocity is slightly below the speed of sound under many hunting conditions. However, under cold air conditions at 32 °F (0 °C), the speed of sound drops to 1,088 ft/s (332 m/s), approximately muzzle velocity. Hence, a "subsonic" round used in these temperatures would 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 1,030 ft/s (310 m/s) or less.
Various combinations of subsonic rounds and semi-automatic .22 LR firearms result in unreliable cycling of the firearms' action, as the result of insufficient recoil energy. Some subsonic rounds use heavier bullets (achieving lower velocities) in order to ensure that, as a result of increased bullet mass, there is enough energy to cycle common blow-back actions. As an example, the Aguila .22 LR SSS "SubSonic Sniper" round, has a 60-grain (3.9 g) bullet on .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 tighter barrel twist (by the Greenhill formula) to ensure that the bullet remains stable in flight.
There are two performance classes of .22 rimfire subsonic rounds. Some subsonic rounds, such as various .22 Short or .22 Long "CB" rounds, give ~700 ft/s (210 m/s) velocity with a 29-grain (1.9 g) bullet providing relatively low impact energy. These may not use any, or only small amounts of gunpowder, and have the characteristics of "zimmerpatronen" or 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 ~950 ft/s (290 m/s) velocity with a 60-grain (3.9 g) bullet offering energy equivalent to many high velocity .22 Long Rifle rounds using standard 40-grain (2.6 g) 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

Standard velocity rounds have a slightly supersonic muzzle velocity of around 1,125 ft/s (343 m/s), and a "normal" bullet weight of 40-grain (2.6 g). 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.

High Velocity

High-velocity, copper-plated .22 LR rounds
The Long Rifle 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 twenty percent (1,200 feet per second (370 m/s) to 1,300 feet per second (400 m/s) while still using the standard 40-grain (2.6 g) solid or 36-grain (2.3 g) hollow point lead bullet.

Hyper velocity

Many .22 LR cartridges use bullets lighter than the standard 40-grain (2.6 g), fired at even higher velocities. Hyper velocity bullets usually weigh around 30-grain (1.9 g) to 32-grain (2.1 g) and can have a muzzle velocity of 1,400 feet per second (430 m/s) to 1,800 feet per second (550 m/s) per second. 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 .22 LR rounds. The Stinger case is longer than that of the Long Rifle (approx. .71 inches (18 mm) versus .595 inches (15.1 mm) for the Long Rifle) but the plated hollow point bullet is lighter and shorter at 32-grain (2.1 g), giving the same overall length as the Long Rifle cartridge. 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 19 inches (480 mm) of barrel length; the powder used in the Stinger increases velocity up to the longest .22 barrel length tested by the NRA, 26 inches (660 mm).)
Later hyper velocity rounds were introduced by other makers based on the Long Rifle case with lighter bullets in the 30-grain (1.9 g) weight range and slow burning rifle powder loadings. The overall length of many of these cartridges was less than the standard overall length of the standard Long Rifle. One example was the Remington Viper.
The CCI Velocitor hyper velocity round uses the standard Long Rifle case size and a standard weight 40-grain (2.6 g) bullet of proprietary hollow point design to augment expansion and trauma for hunting. This cartridge has a muzzle velocity of 1,435 feet per second (437 m/s) per second. Due to the better ratio of bullet mass to air resistance, Velocitor performs better at longer range compared to the light bullets of other hyper velocity rounds.

Shot cartridges

.22 Rat-shot.
Special .22 LR caliber shot cartridges, usually loaded with #12 shot, have also been made. These are often called "rat-shot" or "snake-shot" due to their use in very short range pest control. Such rounds have either 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 shot shells can be used for short range skeet shooting and trap shooting at special, scaled-down, clay targets.

Full metal jacket

During World War II, a full metal jacketed version of the .22 LR was developed for the suppressed High Standard HDM pistol.[9] .

Cartridge construction

The standard .22 rim fire cartridges (BB, CB, short, long, long rifle) differ in construction from most other cartridges in the way the bullet is constructed and held in the case. In "normal" cartridges, the bullet is inserted completely within the "neck" of the cartridge case, being held in place by tension from the case neck around the bullet bearing surface and, in some cases, a small crimp at the very top of the case around a cannelure (groove) in the bullet. Military grade ammunition also use a sealant around the case neck (and primer) to prevent intrusion of moisture (or other foreign matter) that may affect reliability. The sealant also acts as a glue, assisting in bullet retention. Bullets for the standard .22 RF (does not include the .22 Rim Fire Magnum or .22 WRF/.22 Remington Special) are constructed with a "heel" (stem) on the rear of the bullet which is inserted into case and the case mouth is then crimped around that stem, leaving the majority of the bullet bearing surface exposed and making the diameter of the case and the bullet the same (see picture below right). Note that the .22 WMR case diameter is larger than the bullet. This construction method has an inherent weakness in that it provides only minimal protection for the cartridge from exposure to moisture or other elements that adversely affect ammunition reliability. One may take one of these cartridges, hold the case with the fingers of one hand and the bullet between the fingers of the other hand and actually turn (twist) the bullet without turning the case (a little resistance may be encountered at first). This means that the seal between the bullet and case is minimal. Overall reliability of todays rimfire ammunition is extremely high, but is considerably less reliable than centerfire ammunition.

Cartridge length

A .22 Long, .22 LR, and .22 Winchester Magnum, respectively.
The .22 LR uses a straight walled case. Depending upon the type and the feed mechanism employed, a firearm which is chambered for .22 LR may also be able to safely chamber and fire the following shorter rimfire cartridges:
.22 Long Rifle may also be used in firearms chambered for the obsolete .22 Extra Long.
The .22 Winchester RimFire, also called .22 WRF and identical to the .22 Remington Special, and later .22 Winchester Magnum Rimfire, also called .22 Magnum or .22 WMR, use cases different from the .22 LR. The .22 WRF and .22 WMR use a straight wall case, larger in diameter than the "normal" .22 rim fire and does not use a heeled bullet. While .22 WRF may be fired in a .22 WMR, firing a .22 S, L or LR in a .22 WMR firearm will likely result in gas leakage at the breech and may cause a potentially dangerous case rupture. Such use always will result in bullet metal fouling in the .22 WMR chamber throat and degraded accuracy with the smaller rounds.

Usage

Today, .22 LR is mainly being used for hunting small pests, for sports shooting, for plinking, and for inexpensive training. The .22 LR is the choice for several ISSF shooting events: 50 metre rifle three positions, 50 metre rifle prone, 50 metre pistol, 25 metre pistol, 25 metre rapid fire pistol and 25 metre standard pistol; Bullseye, plus divisions of metallic silhouette and pin shooting, most high school, collegiate, Boy Scouts of America, British Air Training Corps, Australian Army Cadets, Appleseed Project and 4H shooting events, and many others. Good quality .22 LR ammunition 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 better suited for use on small game and other small animals;[10] 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 LR cartridges often will work properly only when firing standard or 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 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 .22 LR 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.[11][12]
The Israeli military used a suppressed .22 LR rifle in the 1990s for riot control and to "eliminate disturbing dogs prior to operations," though it is now used less often as it has been shown to be more lethal than previously suspected.[11] Some other examples include the use of suppressed High Standard HDM pistols by the American OSS, which was the predecessor organization of the CIA.[9] Francis 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.

Specifications

.22 Long rifle maximum CIP cartridge dimensions. All sizes in millimetres (mm). The common rifling twist rate for this cartridge is 406 mm (1:16 in), 6 grooves, land width = 2.16 mm, Ø lands = 5.38 mm, Ø grooves = 5.58 mm.
.22 Long Rifle cartridge dimensions in inches.
Muzzle velocity (nominal):
  • 40-grain (2.6 g) lead: 1,082 ft/s (330 m/s) .22 LR Subsonic
  • 36-grain (2.3 g) copper plated lead: 1,328 ft/s (405 m/s) .22 LR High Velocity
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.
According to the official C.I.P. guidelines, the .22 LR case can handle up to 205 MPa (30,000 psi) copper crusher (measuring method crusher conformal) pressure. In C.I.P. regulated countries, every rifle cartridge combo has to be proofed at 125% of this maximum C.I.P. pressure to certify for sale to consumers.
References
  1. ^ a b c d "Federal Cartridge Co.". http://www.federalcartridge.com/ballistics. Retrieved 2007-09-25. 
  2. ^ a b c Simpson,Rich. "Remove pesky rodents with sure-shot rimfire rifles."The Times-News (Twin Falls, Idaho, USA) 2008-03-28.
  3. ^ Kokalis, Peter: Weapons Tests And Evaluations: The Best Of Soldier Of Fortune, page 331. Paladin Press, 2001.
  4. ^ "Forensic Analysis: Weighing Bullet Lead Evidence". Board on Chemical Sciences and Technology. 2004. Archived from the original on 2009-06-10. http://www.webcitation.org/5hQn4z7AA. Retrieved 2007-09-09. 
  5. ^ Simpson, Layne. "Rimfire Hunting Cartridges". Petersen's Hunting. Archived from the original on 2009-06-10. http://www.webcitation.org/5hQn5O2Gn. Retrieved 2007-09-09. 
  6. ^ a b "Hornady's New .17 Mach 2". http://www.chuckhawks.com/17_M2.htm. Retrieved 2007-09-25. 
  7. ^ "BBC NEWS | Northern Ireland | Playground shooter avoids prison". News.bbc.co.uk. Last Updated:. http://news.bbc.co.uk/1/hi/northern_ireland/7092484.stm. Retrieved 2008-09-08. 
  8. ^ "BBC NEWS | World | Europe | Man kills eight at Finnish school". BBC News. November 7, 2007. http://news.bbc.co.uk/1/hi/world/europe/7082795.stm. Retrieved 2008-12-26. 
  9. ^ a b Kokalis, P. G (2002-08). "OSS Silenced Pistol". The Small Arms Review 5 (11). Archived from the original on 2009-09-03. http://www.webcitation.org/5jW8yKn6p. Retrieved 2009-08-25. 
  10. ^ "Federal Premium: Ballistics Detail". http://www.federalcartridge.com/ballistics/Ammo_Ballistics.aspx?id=48&firearm=3&bc=0.139&muzzvel=1240&bulletwgt=40. Retrieved 2007-09-25. 
  11. ^ a b Ruger 10/22 Suppressed Sniper Rifle
  12. ^ SV-99 Sniper Rifle

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