5.56x45 Ammo

Overview of 5.56 NATO Ammo

5.56x45mm NATO is the military specification cartridge adopted by the U.S. Armed Forces in 1964 and standardized by NATO in 1980. It is the standard chambering of the M16, M4 carbine, and virtually every service rifle used by U.S. and allied military forces. Commercially, 5.56 NATO is the most widely owned rifle cartridge in the United States, chambered in hundreds of AR-15 pattern rifle configurations. It fires a .224-inch diameter bullet at high velocity with minimal recoil, covering applications from high-volume range training to precision competition to hunting.

5.56 NATO is loaded to higher pressure than the closely related .223 Remington. A rifle chambered for 5.56 NATO safely fires both 5.56 NATO and .223 Remington ammunition. A rifle marked .223 Remington only should not be used with 5.56 NATO loads. Rifles marked .223 Wylde accept both safely. Always verify your chamber markings before purchasing. For a full breakdown of the differences, see our 5.56 vs .223 guide. If your rifle is a .223 Remington chamber, see our .223 Remington ammo page.

Popular 5.56 NATO Brands We Carry

• Federal 5.56 Ammo: XM193 55gr M193 FMJ in 400-round ammo cans and 1,000-round cases, plus XM855 62gr M855 green tip in 500 and 600-round cases. Federal's Lake City-spec loads are the benchmark for 5.56 range training.
• PMC 5.56 Ammo: X-TAC 55gr FMJ (5.56X) and X-TAC 62gr M855 green tip (5.56K) in 1,000-round cases, plus an 840-round M2A1 ammo can bundle with stripper clips and bandoleers.
• Black Hills 5.56 Ammo: 77gr Tipped MatchKing (D556N19), 62gr Barnes TSX (D556N18), and 70gr GMX (D556N3) in 500-round cases. Small-batch precision loads used by U.S. military special operations units.
• Hornady 5.56 Ammo: Black 75gr OTM and TAP barrier loads for defensive and precision applications.
• Winchester 5.56 Ammo: USA White Box FMJ and M855 green tip loads for range and training use.

Best 5.56 NATO Ammo for Specific Uses

Why Buy 5.56 NATO Ammo from BulkMunitions?

• In stock and ready to ship. We only list ammunition that is physically in our warehouse. No backorders.
• Next-business-day shipping from our Knoxville, TN warehouse on orders placed before our daily cutoff.
• Bulk pricing on M193, M855, and match loads. PMC X-TAC and Federal XM193/XM855 in 1,000-round cases deliver the best per-round pricing on the two most widely used 5.56 NATO loads.
• We tithe 10% of profits to Christian-based, 2A-supporting organizations every quarter, and our customers vote on where it goes.

Frequently Asked Questions

What is the difference between 5.56 NATO and .223 Remington?

5.56 NATO is loaded to higher pressure than commercial .223 Remington. A rifle chambered for 5.56 NATO safely fires both. A rifle marked .223 Remington only should not be used with 5.56 NATO loads. Rifles marked .223 Wylde accept both safely. For a full technical breakdown, see our 5.56 vs .223 guide. If your rifle is a .223 Remington chamber, see our .223 Remington ammo page.

What is the difference between M193 and M855 in 5.56 NATO?

M193 is the original 55gr FMJ load at approximately 3,250 fps. It fragments reliably at close to moderate range and is the more versatile all-around choice. M855 is the 62gr load with a steel penetrator core at approximately 3,000 fps, offering better barrier penetration but less reliable fragmentation at close range. M855 is sometimes restricted at indoor ranges. For general range training, M193 is the better starting point.

Can I shoot 5.56 NATO in a .223 Remington rifle?

Not safely if your rifle is marked .223 Remington only. 5.56 NATO is loaded to higher pressure and can cause dangerous conditions in a .223-only chamber. Rifles marked 5.56 NATO or .223 Wylde fire both safely. Always check your barrel stamp. If you need .223 Remington loads for a .223-only chamber, browse our .223 Remington ammo page.

More About 5.56 NATO Ammo

5.56x45mm NATO originated from a U.S. Army project in the late 1950s to develop a small-caliber, high-velocity cartridge that would give infantry soldiers more rounds per pound of carry weight than the 7.62x51mm NATO while maintaining acceptable terminal performance. Remington Arms developed the cartridge working from an experimental .222 Remington Magnum case, and testing at the Aberdeen Proving Ground demonstrated that the lighter, faster bullet produced superior hit probability in simulated combat conditions. The Army adopted the cartridge as the 5.56x45mm in 1964, chambered in the M16 rifle, and it has served as the standard U.S. military rifle cartridge ever since.

NATO standardization followed in 1980 with the adoption of the SS109 projectile, which became the M855 "green tip" in U.S. service. The heavier 62gr bullet with steel penetrator core offered better performance against light cover and vehicle glass at the longer engagement distances European NATO planners anticipated. The original 55gr M193 load remained in wide use and is still produced today, with shooters and military units selecting between the two based on intended application.

In the U.S. civilian market, 5.56 NATO became the dominant AR-15 cartridge as the platform's popularity grew through the 1990s and 2000s. The AR-15's modular design and the cartridge's combination of low recoil, high velocity, and broad ammunition availability made 5.56 the natural choice for the most widely owned semi-automatic rifle platform in American history. Today more rifles are chambered in 5.56 NATO than in any other centerfire rifle cartridge, and more factory ammunition is produced for it than for any other centerfire rifle caliber in the world.