Lengthened .222 Remington case offering greater powder capacity and velocity. Was a serious contender to become the US military's 5.56mm round before 5.56 NATO standardization.
Type: Rifle
Introduced: 1958, United States
Parent case: .222 Remington
Standardization: SAAMI
Bullet diameter: 0.224" (5.69 mm)
Case length: 1.85" (46.99 mm)
Overall length: 2.28" (57.91 mm)
Max pressure: 54,000 PSI
Rim type: Rimless
Primer: Small Rifle
Typical twist rate: 1:14
Muzzle velocity: 3100–3300 fps
Muzzle energy: 1070–1330 ft-lbs
Effective range: 300 yd
Common bullet weights: 50, 52, 55 gr
Primary use: Varmint, Target
Production status: Active
Also known as: .222 Rem Mag
History: Introduced in 1958 as a longer, higher-capacity version of the successful .222 Remington. Competed directly in the US Army's SALVO project trials against what became the 5.56x45mm NATO. The military selected a slightly different case (which became 5.56 NATO) and the .222 Remington Magnum found its niche as a commercial varmint and benchrest cartridge. Factory ammunition is still produced but in…
Notable firearms: Remington Model 700, Various custom benchrest rifles
Military use: United States (military trials)
Similar cartridges: .222 Remington, .223 Remington, 5.56x45mm NATO