223 Rem

The .223 Remington is a cartridge with almost the same external dimensions as the 5.56x45mm NATO military cartridge. The name is commonly pronounced either two-two-three or two-twenty-three. It is loaded with a 0.224-inch (5.7 mm) diameter jacketed bullet, with weights ranging from 40 to 90 grains (2.6 to 5.8 g) though the most common loading by far is 55 grains (3.6 g).

While the external case dimensions are very similar, the .223 Remington and 5.56x45mm differ in both maximum pressure and chamber shape. The maximum and mean pressures for some varieties of the 5.56 (different cartridge designations have different standards) exceed the SAAMI maximum for the .223 Remington, and the methods for measuring pressures differ between NATO and SAAMI. The 5.56 chamber specification has also changed since its adoption, as the current military loading (NATO SS-109 or US M855) uses longer, heavier bullets than the original loading. This has resulted in a lengthening of the throat in the 5.56 chamber. Thus, while .223 Remington ammunition can be safely fired in a rifle chambered for 5.56x45mm NATO, firing 5.56 ammunition in a .223 Remington chamber may produce pressures in excess of even the 5.56 specifications due to the shorter throat

Suggested Use

• Predators
• Small Game
• Varmint

Performance

According to the official Commission Internationale Permanente pour l'Epreuve des Armes a Feu Portatives (C.I.P.) guidelines the .223 Remington case can handle up to 430 MPa (62,366 psi) piezo pressure. In C.I.P. regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum C.I.P. pressure to certify for sale to consumers. This is equal to the NATO maximum service pressure guideline for the 5.56x45mm NATO cartridge.

The SAAMI pressure limit for the .223 Remington is set at 379.212 MPa (55,000 psi), piezo pressure.