223 and 5.56

[ICEMAN]

Yeah, always confusing. I was given a nice fat box of ammo at xmas, and opened it quickly to check out the round....  I screwed up, it was 5.56 and not .223. So I am sitting on some really nice Federal 5.56 that I cannot shoot. 

[FALFire]

Yeah, always confusing. I was given a nice fat box of ammo at xmas, and opened it quickly to check out the round....  I screwed up, it was 5.56 and not .223. So I am sitting on some really nice Federal 5.56 that I cannot shoot. 

What would you be shooting it in?

[ICEMAN]

A low end Olympic arms .223

I am no AR expert and did not want to risk the higher pressure I assume I would get with the 5.56 ammo...

[FALFire]

I've fired 1000's of rounds of 5.56 ammo through AR's with 223 chambers and never had a problem. Do you believe the Oly Arms is not up to mil-spec standards? Just keep it clean and it should do just fine, it's not going to blow up. Try a mag full and see for yourself.

[ICEMAN]

This is encouraging, thanks FALfire.

[FALFire]

They don't make separate AR15 223 and 5.56 internal parts, they are for the most part, the same and come from the same manufactures, the bolts, bolt carriers, extractors, springs, everything is the same. The differences are in very minor chamber specs which affect the throat and for the most part, unless you have a "custom chamber" with a matched bolt, the 223 chambers cut for the AR15 are so loose they will accept all 223 and 5.56 ammo, This is done to assure there are no problems with off the shelf ammo. Surplus ammo and commercial ammo is made all over the world, do you think they all use the exact same specs? No, they are supposed to keep it within SAAMI specs but how would one know for sure?

Even if you have a 223 chamber and feel the 5.56 ammo will cause a problem, then don't use it. Barrel manufactures are well versed in the likely event that most AR15 shooters will simply pickup the cheapest ammo available to blast through their new toys. I have never heard of any AR15 blowing up using one ammo vs the other in these respective chambers. Most people worry about the 223 vs 5.56 issue like it's an evil demon but never even think about proper head spacing and that is even more dangerous than the ammo differences. Putting a new barrel on an AR that has had 20,000 rounds thru it and not replacing the bolt is asking for potential problems. At most what one might experience with 5.56 vs 223 ammo is accelerated wear, bolt guns, however, may be different.

[Special T]

You also asked about 7.62x39 or the AK-SKS round. Not a long range gun, however a capable gun out to 150-200 yards. The ballistics for a 7.62x39 is much like the 30-30. My little brother has used his AK for deer hunting. Not verry good for long shots, but definitely a possibility of a brush gun. 

[dontgetcrabs]

Found this article after a quick google search:



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 5.56x45 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. 

A shorter leade in a SAAMI spec rifle creates a situation where the bullet in a 5.56 NATO round, when chambered, can contact the rifling prior to being fired.  By having contact with the rifling prematurely (at the moment of firing), chamber pressure can be dramatically increased, creating the danger of a ruptured case or other cartridge/gun failure.

The reverse situation, a .223 Rem round in a 5.56 NATO gun, isn’t dangerous.  The leade is longer, so a slight loss in velocity and accuracy may be experienced, but there is not a danger of increased pressures and subsequent catastrophic failure.

How serious is the danger of firing 5.56 ammo in .223 guns?  Dangerous enough that the SAAMI lists 5.56 military ammo as being not for use in .223 firearms in the technical data sheet titled “Unsafe Firearm-Ammunition Combinations.” 

ATK, the parent company of ammunition manufacturers Federal Cartridge Company and Speer, published a bulletin entitled “The Difference Between 223 Rem and 5.56 Military Cartridges.”  In this bulletin, ATK stated using 5.56 ammo in a .223 rifle could result in “…primer pocket gas leaks, blown cartridge case heads, and gun functioning issues.”

However, the danger may be lower than SAAMI or ATK suggest.  In Technical Note #74 from ArmaLite, the company states “millions of rounds of NATO ammunition have been fired safely in Eagle Arms and ArmaLite’s® SAAMI chambers over the past 22 years,” and they have not had any catastrophic failures.

According to ArmaLite:

“Occasionally a non-standard round (of generally imported) ammunition will fit too tightly in the leade, and resistance to early bullet movement can cause elevated chamber pressures.  These pressures are revealed by overly flattened primers or by powder stains around the primer that reveal leaking gasses.”

What Do You Have?

So, if you own a rifle chambered for the .223 for 5.56, do you know for which caliber it is really chambered? 

Many match rifles are chambered in .223 Remington (SAAMI specs) for tighter tolerances, and theoretically better accuracy. 

Many of the AR-15’s currently sold on the market are made for the 5.56 NATO cartridge.  If you own one of these, you should be fine with any .223 or 5.56 ammunition.

However, ATK dropped this bomb in the bulletin on the .223/5.56:

“It is our understanding that commercially available AR15’s and M16’s – although some are stamped 5.56 Rem on the receiver – are manufactured with .223 chambers.”

So, even if your AR is stamped 5.56, is it really?  Check your owner’s manual or call the company directly and make sure you get an answer you feel comfortable with.

As if the confusion regarding the .223 vs 5.56 chambers wasn’t enough, there is a third possibility in the mix, that is being used by at least one major manufacturer.  The .223 Wylde chamber is a modified SAAMI-spec .223 chamber that allows for the safe use of 5.56 NATO rounds, but maintains tighter tolerances for better accuracy.

Yeah, yeah… What’s the bottom line?

Here’s the bottom line.  If you want to follow the safest possible course, always shoot .223 Remington ammunition.  The .223 Rem cartridge will safely shoot in any rifle chambered for the .223 or 5.56.

If you want to shoot 5.56 NATO rounds, make sure you have a rifle designed for the 5.56 military cartridge.  Shooting 5.56 in a normal .223 Rem rifle can result in bad things.

[FALFire]

Okay.......Now after all that hubbub, do a search and find as many AR15's that you can that suffered major catastrophic failures or have blown up either their barrels or the actions after using 5.56 ammo in a 223 chamber. It will only apply to factory loaded 5.56 or 223 ammo used in 223 chambered guns firing semi auto mode, no reloaded ammo or full auto guns because that stuff is unpredictable. And again, custom tight neck chambers may create a problem.

I've been around these things for many years, fired dozens of AR's using both 223 and 5.56 ammo in opposing chambers and have seen perhaps one or two that displayed any problems which were associated with some crap wolf ammo, the early coated junk that gummed up chambers once they got plenty hot. When you are going through hot combat drills dumping 30 round mags like they were candy and having smoke coming out of the barrel for 20 minutes after shooting there should have been at least one that was a problem.....................But there wasn't 

Again, if you feel unsafe firing 5.56 ammo in a 223 chamber the simple answer is do not do it.

Not saying that it can't happen but if it were a real serious problem someone would have posted the aftermath over and over on the internet.

[rebal69972]

  yep clear as mud.  i think im going to buy 1 in 5.56

[Helix]

I dont remember the reason but like Sebek said. You can shoot .223 and 5.56 out of a 5.56 chamber but should not shoot 5.56 out of a .223 chamber.

Correcto!  The 5.56 chamber has a throat that is cut more generously which allows for a higher pressure loading.  223 rounds will fire through it just fine. However the higher pressure 5.56 rounds can cause overpressure in the tighter 223 throat.