Civilian commercial cartridge dimensionally similar to but distinct from 5.56x45mm NATO. The most popular centerfire rifle cartridge in North America. Lower maximum pressure than military 5.56 — safe to fire in both .223 and 5.56-chambered barrels, unlike 5.56 which should only be fired in 5.56-spec chambers.
Type: Rifle
Introduced: 1963, United States
Parent case: .222 Remington
Standardization: SAAMI
Bullet diameter: 0.224" (5.69 mm)
Case length: 1.76" (44.7 mm)
Overall length: 2.26" (57.4 mm)
Max pressure: 55,000 PSI
Rim type: Rimless
Primer: Small Rifle
Typical twist rate: 1:9
Muzzle velocity: 3000–3900 fps
Muzzle energy: 1100–1350 ft-lbs
Effective range: 600 yd
Common bullet weights: 40, 50, 52, 55, 62, 69, 77 gr
Primary use: Varmint, Target, Competition, Hunting
Production status: Active
Also known as: .223 Rem · 5.56x45mm (commercial)
History: Developed in 1962–63 by Remington alongside the military's development of what would become the 5.56 NATO. SAAMI standardized the civilian .223 Remington in 1963. While the cartridge fed the AR-15/M16 development program, .223 Remington has never been a military-issue designation — the military cartridge is 5.56x45mm NATO. The .223 operates at lower maximum pressure (55,000 PSI vs. 62,000 PSI for…
Notable firearms: AR-15 (civilian), Ruger Mini-14, Savage MSR, Tikka T3x Varmint, Remington 700
Similar cartridges: 5.56x45mm NATO, .222 Remington, .22-250 Remington