.223 / 5.56 NATO

The .223 Remington and its military counterpart, the 5.56x45mm NATO — often written together as .223/5.56 because the conversation always comes up — is the cartridge that America built its modern rifle culture around. It feeds the AR-15, the most popular rifle in the country. It’s used by military and law enforcement forces worldwide. It’s the round that both hardcore competitors and first-time rifle buyers reach for most often. The only downside is how fast you’ll burn through a case of it.

The .223 Remington was developed in 1957 by Remington Arms and Fairchild Industries in response to a U.S. Army request for a small-caliber, high-velocity military cartridge. Eugene Stoner’s AR-15 design was selected to chamber it, and the military version went to Vietnam. Early adoption had problems — wrong twist rates led to reliability issues. The problems were fixed. The round stayed. It’s now the standard cartridge for most NATO militaries and the most popular centerfire rifle cartridge in the United States.

The list is long. Varmint hunting — prairie dogs, coyotes, foxes. Home defense in AR-platform rifles. Three-gun and practical shooting competition. Long-range target shooting with heavy match bullets. Military and law enforcement. Training. And plinking, because burning through .223 in a semi-auto AR is one of shooting’s great simple pleasures. This cartridge does more jobs acceptably well than almost anything else in its class.

Standard loads push a 55-grain FMJ at around 3,240 feet per second. Military M855 runs a 62-grain bullet at 3,025 fps. Common bullet weights range from 40 to 77 grains, giving impressive flexibility. The 77-grain OTM is genuinely capable at 600 yards and beyond. It’s marginal on deer but devastating on everything smaller.

Name a major ammunition manufacturer and they make .223/5.56. Federal, Hornady, Winchester, Black Hills, PMC, Fiocchi — the options are essentially without limit. Bulk 55-grain FMJ is your everyday training ammo. Hornady’s 75-grain BTHP is match-grade. Buy it by the case. You’ll use it.

Affordable, accurate, versatile, and available everywhere. The AR-15 platform gives you modularity and aftermarket support that no other rifle system can match. Low recoil means long range sessions without fatigue. And the sheer variety of loads — from 40-grain varmint grenades to 77-grain match bullets — means one rifle can genuinely do it all. Also, it’s just fun. There’s no other way to say it.

Arms East keeps a deep inventory of .223 and 5.56 NATO ammunition because our customers shoot a lot of it. We carry everything from bulk training FMJ to match-grade precision loads and defensive hollow points. Whether you’re building your first AR or fine-tuning a competition rifle, come see us. We know this round and the rifles that shoot it.