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The development of .223 Remington and 5.56X45mm NATO ammo
Is there another rifle in the United States as talked about as the AR-15? To the uneducated, it is mislabeled as an assault rifle. Gun enthusiasts know that the AR stands for Armalite Rifle. Armalite and the .223 cartridge were developed together in the late 1950s for the US Army. The Army was seeking a small-caliber, high-velocity firearm and cartridge that could exceed the supersonic speed at 500 yards and penetrate an Army steel helmet at the same distance. Eugene Stoner of Armalite took the lead on the development of the rifle while Remington Arms took the lead on the development of the cartridge. Through trial and error came the AR-15 and the .223 Remington cartridge.
Worldwide use of .223 and 5.56
In 1960, the first AR-15’s and .223 were used in the Federation of Malaysia. In 1961, the combo was sent to Vietnam for limited testing (only 10 rifles were used by the U.S. Army). That same year, 8500 were commissioned for use by the U.S. Air Force. In 1963, the M-16, along with 5.56X45mm NATO ammo, was born. Over time, the M-16 became the standard issue in all 4 branches of the U.S. military and other militaries and police forces all over the world. In 1963, Remington introduced its civilian version of the ammo for “varmint and small game hunters”. They released the .223 cartridge for use in the Remington model 760 pump action rifle. Since then, most manufacturers of rifles have had at least one firearm chambered for .223, making this one of the most popular rifle cartridges in the world.
.223 Remington vs 5.56X45mm NATO
Though these two cartridges are almost identical, there are differences. The 5.56 has a stamped ring around the primer to ensure that the primer won’t back out on full auto. Another difference is in the pressures produced when firing. The .223 produces a pressure of about 55,000 PSI, while the 5.56 produces a pressure of about 63,000 PSI. Thus, you can substitute the .223 in a rifle designed to fire the 5.56 NATO, but you can’t substitute the other way around. Some rifles are designed to fire both without any issues (sometimes referred to as 223 Wylde). Both cartridges come in a variety of weights and arrangements.