is not as accurate as .223 Remington in many of the AR-type rifles extant, even with the same bullet weight. The .223 Wylde chamber specification developed by Bill Wylde solves this problem by using the external dimensions and lead angle as found in the military 5.56×45mm NATO cartridge and the 0.224 inch freebore diameter as found in the civilian SAAMI .223 Remington cartridge. It was designed to increase the accuracy of 5.56×45mm NATO ammunition to that of .223 Remington. Other companies also have chamber designs that increase 5.56×45mm NATO accuracy. Comparisons The table contains some estimated pressures based on normal proofing practice and on the known increases in pressure caused by bullet setback (which is a similar occurrence with regard to pressure). The proof pressure of M197 is 70,000 psi. The following table shows the differences in nomenclature, rifling, throating, and normal, maximum, and safe pressures: Beside the NATO EPVAT testing pressure testing protocols the other employed peak pressure measurement methodology or methodologies to correlate this table remain unknown. 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". In the case of the 223 Remington (M193), ammunition loses or gains about 25.7 ft/sec for each inch of barrel length, while 5.56×45 mm NATO (M855) loses or gains 30.3 ft/sec per inch of barrel length. Usage and commercial offerings The .223 Remington has become one of the most popular cartridges and is currently 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, Remington XP-100, etc. The popularity of .223 Remington is so great, that in the US it virtually eliminated all 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 Sierra Matchking bullets are available for reloaders. See also .30 RAR 5 mm caliber 6×45mm Delta L problem List of rifle cartridges Sectional density Table of handgun and rifle cartridges References 100's of 223 Ammo products are listed here. 223 Ammo External links .223 Remington Cartridge Guide