.223 Remington

The .223 Remington is a sporting cartridge of almost the same physical dimensions as the 5.56 x 45 mm NATO cartridge but with a difference in the "lead" of the chamber throat. The .223 Remington can be safely fired in a 5.56 mm chamber, but the reverse is an unsafe combination that causes extreme pressures and could damage or destroy the rifle. The .223 Remington is also loaded to slightly lower velocities than 5.56 mm in most commercial loadings.

History

The .223 Remington was developed as an enlarged and higher velocity version of the .222 Remington, which had existed in the 1950's as a varmint cartridge. The .223 Remington was developed specifically for the Armalite AR-15, which later became the U.S. military rifle M-16.

Uses

The .223 Remington is one of the most common rifle cartridges in use in the United States, being widely used in two types of rifles: (1) varmint hunting rifles, most of which are bolt action and commonly have 1-in-12 rifling twist suitable for bullets between 40 and 55 grains, and (2) semiautomatic rifles such as the AR-15 and the Ruger Mini-14, which commonly have twist rates of 1-in-9 suitable for bullets from 50 to 75 grains. The latter category are often used by law enforcement, for home defense, and for varmint hunting (especially farm and ranch work, after which Ruger named a version of its Mini-14 the "Ranch Rifle"). .223 Remington ammunition is among the least expensive centerfire calibers and is often used by avid target shooters, particularly in the "high power rifle" category.

See also

• M-16
• Armalite AR-15
• Ruger Mini-14