.223 Remington vs 5.56 NATO: What's the Difference?

Put a .223 Remington round next to a 5.56 NATO round and you will have a hard time telling them apart. They are the same size on the outside. The difference is pressure and chamber shape, and that difference decides which rifle can safely shoot which round.

How the two rounds differ

The .223 Remington is a civilian cartridge built to industry specs. The 5.56 NATO is the military version of the same case. It is usually loaded to higher pressure.

Rifles are built to match. A 5.56 chamber has a little more room in front of the bullet, called the throat or leade. That extra room keeps pressure in check when a hotter 5.56 round goes off. A .223 chamber is tighter.

“Same outside, different inside.”

Which rifle can shoot which round

• Rifle marked 5.56 NATO: can shoot both 5.56 and .223. The .223 may be slightly less accurate in some rifles, but it is generally considered safe.
• Rifle marked .223 Remington: should shoot .223 only. Firing 5.56 in a tight .223 chamber can push pressure past what the rifle was built for.
• Rifle marked .223 Wylde: a hybrid chamber made to shoot both well.

The marking on the barrel tells you which chamber you have. Read it, and check the maker's manual. If the barrel says only .223 Remington, stick with .223 ammo.

“Read the barrel before you buy the box.”

Where each round fits

Many 5.56 loads are full metal jacket rounds made for practice and range time. They are a common pick for high-volume shooting.

The .223 shelf has more variety in bullet type. You will find match bullets for paper targets, light varmint bullets for small game, and soft points for hunting where the caliber is legal. If you shoot for accuracy or hunt small game, start on the .223 page.

What about price?

In our listings, 5.56 often costs less per round than .223 from the same brand. The chart at the top shows it brand by brand. That gap is one reason owners of 5.56 rifles shoot a lot of 5.56. If your rifle is marked .223 only, a lower price is not a reason to switch.

To compare fairly, sort by price per round and match bullet weight and type. Brand pages like Federal .223 and Federal 5.56 put one maker's loads side by side.

“When in doubt, shoot .223 or ask the maker.”

Quick answers

• Can I shoot .223 in a 5.56 rifle? Generally yes.
• Can I shoot 5.56 in a .223 rifle? Not recommended. Use .223 unless the maker says otherwise.
• Are the bullets the same size? The bullet diameter is the same. Pressure and chamber specs are what differ.

Ready to compare? See live .223 Remington listings or see live 5.56 NATO listings. Shopping for the rifle itself? Browse 5.56 rifles and .223 rifles.