About the bullets
The .223-caliber Remington and .22-caliber Long Rifle bullets are the same width, and both can be fired from semi-automatic guns. The casing on the .223-caliber Remington is larger to include more powder, allowing it to fire from guns at a higher velocity. The .223-caliber Remington and the 5.56 NATO are ballistically identical.
BULLETS ARE ACTUAL SIZE
The .223-caliber Remington originated as a military cartridge but has become popular for varmint hunting and competition target shooting. Because of its low recoil, the AR-15 is increasingly popular for deer hunting, especially among children. The .223-caliber is the standard cartridge for AR-15 style rifles, but it is also available in bolt-action repeaters, single-shot break-action rifles, single-shot and bolt-action handguns.
5.56 x 45-caliber (5.56 NATO) The 5.56-caliber x 45-caliber (5.56 NATO) cartridge can be used in the M16 rifle and the AR-15. The cartridge is identical on the exterior to the .223-caliber Remington and fires the same bullets. The .223-caliber cartridge will chamber in 5.56-caliber rifles and vice-versa but 5.56-caliber cartridge walls are thicker, which means the cartridge holds less gunpowder than the .223-caliber Remington but can tolerate higher pressure. The 5.56-caliber NATO can be used for hunting, but it is not as popular as the .223-caliber Remington for hunting.
The .22-caliber Long Rifle is a favorite of those who hunt small game, such as squirrels or raccoons. It is available in bolt-action rifles, semi-automatic rifles, semi-automatic pistols and revolvers. It is generally used at ranges of less than 50 yards.