.223 Remington

Development The development of the cartridge, which eventually became the .223 Remington, was linked to the creation of a new small-caliber, high-velocity (SCHV) combat rifle. Work on a rifle and cartridge to meet the requirements of the U.S. Continental Army Command (CONARC) began in 1957. Fairchild Industries, Remington Arms, Winchester, and several engineers (including Eugene Stoner of ArmaLite, who was invited to scale down the AR-10 (7.62×51mm NATO) design). contributed. CONARC ordered rifles to test. Stoner and Sierra Bullet's Frank Snow began work on the .222 Remington cartridge. Using a ballistic calculator, they determined that a 55-grain bullet would have to be fired at 3,300 ft/s to achieve the 500-yard performance necessary. ==Cartridge dimensions==

The .223 Remington has a 1.87 mL (28.8 gr H2O) cartridge case capacity. Americans would define the shoulder angle at alpha/2 = 23 degrees. The common rifling twist rate for this cartridge is 305 mm (1 in 12 in), 6 grooves, Ø lands = , Ø grooves = , land width = and the primer type is small rifle. According to the official CIP rulings, the .223 Remington can handle up to Pmax piezo pressure. In CIP-regulated countries, every rifle cartridge combination has to be proofed at 125% of this maximum CIP pressure to certify for sale to consumers. Remington submitted .223 Remington specifications to SAAMI in 1964. ==.223 Remington vs. 5.56×45mm NATO==

In 1980, the .223 Remington was transformed into a new cartridge and designated 5.56×45mm NATO (SS109 or M855). Pressures Remington submitted the specifications for the .223 Remington cartridge in 1964 to SAAMI. The original pressure for the .223 Remington was 52,000 psi with DuPont IMR Powder. A higher pressure of resulted from the change from IMR to Olin Ball powder. Chamber pressures obtained using different methods are not comparable. The pressure limits for .223 Rem and 5.56×45mm NATO are very similar, if using similar measurement methodologies. • The SAAMI sets the pressure limit for .223 Rem at , using a chamber conformal transducer. • The CIP sets the pressure limit for .223 Rem at , using a perforated-case transducer. Chambers The .223 Remington and 5.56×45mm NATO barrel chamberings are not the same according to Clymer, with the 5.56 NATO chamber having generally slightly larger dimensions. A brochure from "Forster Products" claims that while the headspace gauge for .223 Rem is 1.4636/1.4666/1.4696 for Go/NoGo/Field, the gauge is 1.4636/1.4736 for Min/Max on 5.56 NATO. The brochure goes on to claim that this could mean a premature contact with rifling with 5.56 ammunition if fired from a .223 chamber. However, the 2025 SAAMI specification for the headspace dimension on .223 Rem is the same as what Forster claimed for 5.56 NATO: 1.4636 to 1.4736. Other companies also have chamber designs that increase 5.56×45mm NATO accuracy. (The "lower accuracy" observation for 5.56 chambers running .223 ammunition has not been reproduced with newer tests.) Andrew of LuckyGunner LLC has collected 8 different chamber dimensions from various reamer companies, including .223 Rem, .223 Wylde, and 5.56. He also emphasizes that manufacturing differences will make each actual chamber dimensionally different from others. In addition, he tested 5.56 NATO ammunition in .223 Rem chambers and failed to find dangerous levels of pressure increase. Rifling NATO chose a 178-mm (1-in-7) rifling twist rate for the 5.56×45mm NATO chambering. The SS109/M855 5.56×45mm NATO ball cartridge requires a minimum 228 mm (1-in-9) twist rate, while adequately stabilizing the longer NATO L110/M856 5.56×45mm NATO tracer projectile requires an even faster 178 mm (1-in-7) twist rate. The following table shows the differences in nomenclature, rifling, throating, and normal, maximum, and safe pressures: Key to peak pressure measurement methods: • EPVAT: NATO EPVAT testing at case mouth. • CCT: chamber conformal transducer. Includes: SAAMI method and SAAMI-like "SCATP" method used by the US Army. • CIP: CIP drilled-case. • MCSG: mid-case strain gauge, appears to generate slightly higher readings than SAAMI. • (no marking): unknown, hence difficult to compare. Notes: • "Rifling" and "throat", like chamber dimensions, should be attributes of the firearms themselves, and not of the ammunition. This probably refers to "intended" values for the ammunition. ==Effects of barrel length on velocity==

Barrel length helps determine a specific cartridge's muzzle velocity. A longer barrel typically yields a greater muzzle velocity, while a shorter barrel yields a lower one. The first AR-15 rifles used a barrel length of 20". ==Usage and commercial offerings==

, .308 Winchester The .223 Remington has become one of the most popular cartridges. It is used in a wide range of semiautomatic and manual-action rifles and even handguns, such as the Colt AR-15, Ruger Mini-14, Remington Model 700. For example, the cartridge has become widely used in the US, significantly reducing the prevalence of other similar .22 caliber center-fire varmint rifle cartridges. It is commercially loaded with 0.224-inch (5.7 mm) diameter jacketed bullets, with weights ranging from 35 to 85 grains (2.27 to 5.8 g), with the most common loading by far being 55 gr (3.6 g). Ninety-grain and 95-grain (6.2 g) Sierra Matchking bullets are available for reloaders. ==See also==