During the late 1950s, ArmaLite and other U.S. firearm designers started their individual Small Caliber/High Velocity (SCHV) rifle experiments using the commercial .222 Remington cartridge.

With the U.S. military adoption of the M16 assault rifle in 1963, the .223 Remington in a slightly derived form was standardized as the 5.56×45mm NATO.

Case capacity is about 5% smaller than that of the .222 Remington Magnum, but it was loaded to a slightly higher pressure, so the two have essentially identical ballistics.

For many .222 Magnum shooters handloading of this cartridge provides ammunition, using components otherwise available for the other more popular .22 centrefire rounds.

The .204 Ruger is based on the .222 Remington Magnum case necked down to hold a .20 caliber (5 mm) bullet.