The AR-15 comes in many sizes and has many options, depending on the manufacturer. The part shown bottom center is the lower receiver with pistol grip and trigger assembly.
|Place of origin||United States|
|Designer||Eugene Stoner, Jim Sullivan, Bob Fremont|
|Manufacturer||ArmaLite, Colt, Bushmaster, Rock River Arms, Stag Arms, DPMS Panther Arms, Smith & Wesson, Ruger, Anderson, Daniels Defense, CMMG, Olympic Arms, DSArms, Palmetto State Armory, Spike's Tactical, and others.|
|Mass||2.27 kg–3.9 kg (5.5–8.5 lb)|
|Cartridge||5.56×45mm NATO and others; see list of AR platform calibers|
|Action||Direct impingement or Gas Piston / Via a Rotating bolt|
|Rate of fire||Depends on operator's speed when pulling trigger.|
|Muzzle velocity||975 m/s (3,200 ft/s)|
|Effective firing range||400–600 m (avg 547 yd)|
|Feed system||Various STANAG magazines. 5–100-round capacity|
|Sights||Adjustable front and rear iron sights|
The " AR" in its name reflects the first two letters in the company name... ArmaLite. The fact that the AR-17 is a shotgun gives lie to a common belief that AR stands for "ArmaLite Rifle."
The military version is the M-16, manufactured by Colt Firearms, FNMI, Harrington Richardson, Daewoo, and others.
The AR-15 is a semiautomatic rifle that discharges a single shot with each pull of the trigger until empty. The M-16, unlike the AR-15, is a select fire (semi and fully automatic) magazine fed, gas operated, shoulder fired assault rifle. The M-16 first saw combat in the Vietnam War.
The AR-15 is a lightweight, magazine-fed, air-cooled rifle with a rotating locking bolt actuated by propellant gas expanding within an internal gas piston operating system.
The gas for this system is tapped from the barrel and travels down a gas tube that feeds it into the bolt carrier and thus the gas (i.e. piston) cylinder. The gas expands within the piston cylinder and forces the carrier rearward. A cam pin linking the bolt to unlocking surfaces of the bolt carrier forces the bolt to unlock from the barrel and allows the assembly to drive to the rear.
An error in an early article covering the AR-15 described the system as a "direct impingement" system. This long standing error is based on the fact that a true direct impingement system also moves propellant gasses from the barrel into the face of the carrier. Unlike pressurizing a piston cylinder in the bolt carrier, the gas of the direct impingement system simply passes into a shallow depression in the bolt carrier and actually blows the carrier to the rear.
Early usage of the M16 version of the AR-15 in Viet Nam resulted in intense criticism of poor reliability. On-scene studies revealed that the barrel and chamber tended to accumulate rust pits in the humid conditions in Viet Nam that caused difficult extraction of fired cartridge cases. Chrome plating of the barrels and chambers solved the problem and the M16 has gone on to great approval. While the early AR-15s also were built with un-chromed barrels the moderate climate in the US and gentler use by owners resulted in few problems.
Barrels of current commercial variants of the AR-15 are produced in chromed, un-chromed, and stainless steel barrels with little extraction difficulty in the more moderate climate in the US.
Even the earliest AR-15 and M16 internal piston systems were chromed plated and the rifles performed well if properly lubricated and cleaned. Nonetheless some rifle manufacturers have accused the internal piston system of inferiority and modified the rifles to an external piston system and driving rod pushing the carrier.
Two such designs were developed for the military and found unneeded. Extreme test firing (2000 rounds with no cleaning or lubing and no malfunctions) confirmed findings that simple lubrication keeps the rifles functioning for extreme periods, but all manufacturers recommend more frequent cleaning.
First considered of little use, the AR-15 was long considered to provide inferior accuracy to target shooters in the prestigious Service Rifle matches. The provision of heavier match barrels and target sights by ArmaLite and heavier match bullets by the Sierra Bullet company produced accuracy so satisfactory that they have displaced the previous M1 and M16 rifles used in those matches. The
The AR-15s light weight, accuracy, and light recoil has made it extremely popular with shooters and its use is spreading around the world. It is a useful collector's item, ranch or home secuity rifle, and small caliber hunting rifle and has become one of the most popular rifles in the world, and ArmaLite's are manufactured even today.
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- 30 Caliber Magazine Clip in a Half Second! (With the world's FASTEST shooter, Jerry Miculek). YouTube. February 6, 2014.
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