.223 Remington vs. 5.56 NATO: What You Don’t Know Could Hurt You

Bearing Arms ^ | 13 Feb, 2015 | Bob Owens

[MtnClimber]

Is firing a 5.56 NATO cartridge in your .223 Remington chambered AR15 dangerous? Or do Internet forum-ninjas and ammunition companies selling you commercial ammo instead of surplus overstate the dangers? Believe it or not, a real danger exists, and some gun owners who think they are doing the right thing may not be safe.

The Cartridges

The .223 Remington and 5.56×45 NATO cartridges are very similar, and externally appear the same. But there are some differences that lie beneath the surface.

The 5.56 case has thicker walls to handle higher pressures, meaning the interior volume of the case is smaller than that of a .223. This will alter the loading data used when reloading 5.56 brass to .223 specs.

Some 5.56 loads have a slightly longer overall length than commercial .223 loads.

The Chambers

The significant difference between the .223 Rem and 5.56 NATO lies in the rifles, rather than the cartridges themselves. Both the .223 and 5.56 rounds will chamber in rifles designed for either cartridge, but the critical component, leade, will be different in each rifle.

The leade is the area of the barrel in front of the chamber prior to where the rifling begins. This is where the loaded bullet is located when a cartridge is chambered. The leade is frequently called the “throat.”

On a .223 Remington spec rifle, the leade will be 0.085”. This is the standard described by the Sporting Arms and Ammunition Manufacturers’ Institute, Inc. (SAAMI). The leade in a 5.56 NATO spec rifle is 0.162”, or almost double the leade of the .223 rifle.

[Vendome]

In a modern Era Springfield?

I was told I could shoot anything.

[MtnClimber]

Thanks, and one of my .308’s is a Springfield M1A.

[Carriage Hill]

Here’s a better and more technical explanation of 5.56 v .223 ammo:

http://www.luckygunner.com/labs/5-56-vs-223/

[SkyDancer]

Marines. Pacific. He’s 94 now.

[MtnClimber]

Thanks for the link. That was good information.

[TonyM]

If the barrel is not stamped 5.56 then don’t put a 5.56 cartridge in it. It really is that simple. A 5.56 barrel can handle the pressure from a .223 but a .223 barrel cannot handle the pressure from a 5.56.

[dangerdoc]

Yeah, it applies to all models and manufacturers. The gas is tapped at a point in the barrel which starts the rifle cycling. With ball ammo, the slug is gone before the action unlocks. I’ve read that if you want to shoot heavier ammo, there is a piston replacement. I can’t remember at what weight a piston replacement is recommended.

[Elderberry]

My Dad, Navy, Pacific, passed away.

[snuffy smiff]

A while back Ruger made a carbine available in both 9mm and .40S&W. Both were designed to use same magazine as their respective pistols. Despite a few drawbacks, the few that do come up for sale usually don’t linger for very long.

[Vendome]

I’ll look into that...

Never knew...

[MtnClimber]

I specifically bought a 5.56 to avoid the potential issues of buying .223 and using both ammo. So far I have strictly used 5.56 ammo in my Armalite Eagle-15. From what I have read the .223 would produce lower pressures and no reloading problems. Seems you could shoot .223 with no problems.

[sarge83]

If your rifle is chambered for 5.56 you can safely use .223. if it is chambered for .223 you shouldn’t use 5.56.

[dangerdoc]

Lots of info out there, there is an M14 forum with tons of info applicable to the M1A.

[sarge83]

You will bend your slide rod using commercial 30’06 in a grand unless you put an adjustable gas plug on it. Use military grade ammo otherwise the powder burns at a different rate than commercial 30’06. You can get has plug at Midway $40-$50 range.

[jonno]

bookmark

[glock rocks]

I always fill with premium.

Hell, I bought a V8.

[tumblindice]

Or you could ream the chamber for a longer leade if your barrel is marked `.223’ and checks out as .223.
Complicating matters further, your barrel may say 5.56 but actually be .223 so a tool to check it might be a good idea, as shown here:
http://www.gunsandammo.com/gunsmithing/5-things-to-check-on-your-ar-15/
Or a gunsmith might do it for you for a few bucks. It’s something like a `Go/No go’ headspace gauge.
(Commercials at the site, but what are you gonna do?)

[glock rocks]

.308 is my choice over the nato. Just the opposite with the .223.

[JonPreston]

Can you give me a couple of examples of a medium quality 5.56 rifle? The easier to operate the better. Thanks.

[glock rocks]

Rock River