.223 Remington--Centerfire Favorite The .223 Remington is the most widely-used centerfire rifle cartridge in the developed world. In its 5.56x45 military form, it is the primary issue ammunition for the U.S. Military and NATO forces. It is a popular sporting cartridge, and probably the most commonly used centerfire varmint cartridge. In our Readers' Poll, the .223 Rem (both standard and improved) ranked first among preferred varmint rounds. The .223 Rem is efficient and versatile. It can sling 40-grainers past 3650 fps, and deliver 90gr VLDs accurately at 1000 yards. Its parent case, the .222 Remington, was once a mainstay of benchrest competition. Today, with custom match bullets, the .223 Remington can still deliver impressive accuracy, shooting well under quarter-MOA in a good rifle.

.223 Remington Cartridge History The .223 Rem traces its roots to the .222 Remington, a round popular with benchrest and varmint shooters in the 1950s. When the US military was looking for a new high-speed small-caliber round to replace the .308 Winchester (7.62x51), Remington started with the .222 Remington, and stretched it to increase powder capacity by about 20% in 1958 to make the .222 Remington Magnum. The cartridge was not accepted by the military, but it was introduced commercially. In 1964, the 5.56x45 mm, also based on a stretched .222 Rem case (and very similar to the .222 Rem Magnum), was adopted along with the new M-16 rifle. As with the .222 Rem Magnum, the new military case achieved enhanced velocity (over the .222 Rem) by increasing case capacity with a longer body section and shorter neck. This military modification of the .222 Rem was originally called the .222 Special but was later renamed the .223 Remington. In military metric nomenclature, the round is called the 5.56x45. For the full history of the 5.56x45 cartridge, read the 5.56x45 Timeline, by Daniel Watters.

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