.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.

[Elderberry]

I have the adjustable gas plug, but I've yet to install it. All I've run thru it is a case of the Hornady AMax Garand. And I have around 500 rds of delinked surplus I picked up from http://www.ammogarand.com/

[Squantos]

My Rock River Fred Eichler is .223 Wylde ..... extremely accurate rig right out of the box. The cut coyote tracks on the hand guard make it just darn cool ! Wiley Coyote hates me !

http://files.harrispublications.com/wp-content/uploads/sites/8/2013/10/RRA-LAR-15.jpg

[ChildOfThe60s]

RRA LAR 15 with a Wylde Chamber. I’ve shot thousands of rounds of .223 & 5.56 Nato through it.

[smokingfrog]

cool shoulder thing that goes up!

[Big Red Badger]

Plenty out there ,
buy soon if you live in
California.

[aposiopetic]

ping

[Billthedrill]

Ooooh...ain’t that purdy? Just got a Rock River lower (national match trigger) for my next build. It’s going to be a target/varmint build. What glass you gotcha there if I may ask?

[Squantos]

? talking about the QD push lock for the sling ?? Thats a file pic, not mine but identical shy of accessories. Running a 6-18X Leupold AR optic and a harris bipod with a drop cord for fast deployment. Most of the time I use a Stoney Point X bag off the hood of the truck ..... Roll my own fodder when I finally found the recipe that 1 in 8 twist liked ....... sweet rig.

[Squantos]

See # 68.....

[sarge83]

The Ruger 556, S&W MP Sporter are good choices with good warranties, also armalite ar and Palmetto state armory hardware is good stuff.

[Billthedrill]

Many thanks. I want.

[Squantos]

https://www.leupold.com/hunting-shooting/scopes/mark-ar-riflescopes/mark-ar-mod-1-6-18x40mm/

Great scope ..... got the fine flex reticle versus the mildot . About 5 bills on the street versus the 600$+ MSRP.

[Charles Martel]

The mil-spec brass is thicker for added reliability. The chamber leade is more gradual because match-rifle accuracy isn’t expected or required in an assault rifle. I suspect the leade was set based on torture tests and the effects of heavier use (read: barrel fouling and minimal cleaning) than a commercial .223 would see. Plus, there has always been a tiny bit of weirdness within NATO, where member countries adopt their own, home-brewed version of the “standard” ammo. Stuff like overall cartridge length is the same, but bullet ogive may be different.

[smokingfrog]

I was mocking Carolyn McCarthy.

http://youtu.be/ospNRk2uM3U

[Elderberry]

It looks like quite a rig.

I just got my Son to help me put together my first AR. I went with an Alexander Arms 6.5 Grendel Overwatch Upper, an Anderson lower, and a Rock River NM trigger. I stuck on an old 15X Weaver target scope to rush it to the range. I'm pretty happy with it so far. Now I need to get a proper scope for it.

[Rome2000]

I'm going with this one for the car trunk in the city, the 7.62 x 39 (AK Platform) is not great for urban situations.

"The IWI Tavor has been in service with the Israel Defense Forces (IDF) since 2001. Now IWI US is offering the Tavor SAR, a semi-auto version, to American citizens. It employs a long-stroke piston operating system and uses standard AR magazines. SARs are available with 16.5- or 18-inch barrels, and shooters can choose a model with a flattop or a Mepro 21 reflex sight. (iwi.us; 717-695-2081)"

Specifications: IWI Tavor SAR

Caliber: 5.56mm NATO

Barrel: 16.5 or 18 inches

OA Length: 26.13 inches

Weight: 7.9 pounds (empty)

Stock: Synthetic

Sights: Flip-up front and rear

Action: Black or Flat Dark Earth

Finish: Missing copy

Capacity: 30+1

MSRP: $1,999

[bobby.223]

Nice choice.

[JonPreston]

$1,749.00 on Gunbroker.com

[GunsAndBibles]

It should be stamped right on the barrel, at least mine is.

Easy mnemonic: math
.223 goes into 5.56; but 5.56 does not go into .223

[Squantos]

6.5 Grendel is a great caliber ..... old Weavers are hidden gold. Love em. Sounds like a great rifle build.