The AR in AR-15 stands for Armalite Rifle.
The AR does not stand for or mean assault rifle or automatic rifle.
AR-15 and other semi-automatic rifles are NOT “assault weapons” or “assault rifles.”
An assault rifle is fully automatic — a machine gun.
Automatic firearms have been severely restricted from civilian ownership since 1934.
Under US law, when manufactured with a barrel length less than 16 inches (410 mm) and without a shoulder stock, it is legally considered a pistol as opposed to being a short-barreled rifle, and is described as an AR-15 style pistol.
The lower receiver is legally defined as a firearm under United States federal law.
The 5.56 is the original decade standard for the AR-15 caliber.
This round is very light, and considering that the AR-15 holds 30 rounds, the AR-15 can carry a couple hundred 5.56 with no problem at all.
Most AR-15-type rifles are sold with a 30-round magazine, but it is possible to purchase after-market magazines with as many as 100 rounds.
Unlike the musket's lead ball, the bullet from an AR-15 leaves the muzzle at 3,300 feet per second.
That's three times the speed of a modern handgun bullet.
Which means it has plenty of energy to do damage inside a body.
The distance an AR 15 can shoot accurately greatly depends on the rifle makeup, ammunition, and shooter.
It is known as the effective range of the rifle.
But generally speaking the effective range of an AR 15 with standard Mil-spec build chambered in . 223 is 400-600 yards.
The Colt AR-15 uses 20- or 30-round staggered-column detachable box magazines.
Low-capacity 5- or 10-round magazines are also available to comply with legal restrictions, for hunting, for benchrest shooting or where a larger magazine can be inconvenient.