.223 / 5.56 NATO

[jimmyj]

What is the differences ??

 

[pasote]

5.56 chamber has a longer leade and round has more pressure

What is the differences ??

The leade on the 5.56 is longer and the round is loaded to higher pressures than the .223. You can shoot .223 in a 5.56 chamber but you cant shoot 5.56 in a .223 chamber. Too much pressure.
Cheers! Good Shooting!

 

[WR Moore]

As above, the chamber freebore is longer, the angle of the rifling ends is different, there are very slight differences in some other dimensions of the chamber.

5.56 x 45 mm ammunition has a maximum chamber pressure about 5K higher, per some sources, than .223. Doesn't necessarily mean each and every lot of ammunition is loaded to that pressure. Dimensonally, both cartridges are the same.

 

[ArchAngelCD]

Yes, they are the same dimensionally and the evidence is, there are no 5.56x45mm dies only .223 Remington dies.

 

[Fishinfool]

One was designed for killing communists, and has transitioned to killing terrorists pretty well. The other is for killing woodchuck's. Or something like that...

Larry

 

[Oldsalt66]

This detailed article hits all the bases:

223 -vs- 5.56: FACTS and MYTHS – Ultimate Reloader

 

[DWalt]

The leade on the 5.56 is longer and the round is loaded to higher pressures than the .223. You can shoot .223 in a 5.56 chamber but you cant shoot 5.56 in a .223 chamber. Too much pressure.
Cheers! Good Shooting!

Not so. Military NATO ammo chamber pressure measurement methods are different from SAAMI measurement methods. Apples to apples, peak pressure limits are the same for military vs. commercial ammo. The main difference is in the chamber leade dimensions.

 

[stansdds]

The primary difference is the chamber, longer lead in the 5.56 NATO chamber.

 

[9mmPatriot]

This detailed article hits all the bases:

223 -vs- 5.56: FACTS and MYTHS – Ultimate Reloader

Ya beat me to it....


Gavin is legendary!

 

[WR Moore]

IIRC, the "can't shoot 5.56 x 45 mm in a .223 chamber" was started when folks tried shooting the military ammo in a .223 Thompson Center Contender. No one was specific about what happened, but TC took out print ads advising against the practice.

The linked article has what I expect is a slight error in the genesis of the .223/5.56 x 45 mm round. Some years back there was a long article on this subject in the American Rifleman. Remington (and Winchester) had been working for some time in the 1950's on a .22 center fire cartridge for the DOD Light Rifle Project referred to in the article as CONARC. Remington won the cartridge design competition. Which rifle to adopt remained open.

The Pentagon then shelved the Light Rifle project, probably Congress driven due to recent/pending adoption of the M14 & the fight for NATO standardization of the 7.62 x 51 mm cartridge. I'll skip the rest of the political high jinks that got the AR/5.56 into military service.

At some point during that skulduggery, Remington apparently-per the linked article- decided to release the .223 as a commercial cartridge, possibly/probably anticipating the sales surge that results from military adoption. (Also cutting the legs out from under their .222 Magnum and later, the .222.) But, the .223 really was NOT the parent cartridge of the 5.56 x 45 mm.

 

[TX-Dennis]

Stay away from tracer or other specialty military rounds and the difference is insignificant. Your standard 55 or 62 grain NATO rounds will not harm your .223 chambered weapon.

 

[diyj98]

The 5.56 normally has a thicker case and won’t hold quite as much powder as a 223 after both have been ran through the same resizing die.

I’ve shot plenty of standard 5.56mm in 223 bolt action and single shot rifle with zero problems.

 

[WR Moore]

That's not necessarily true and may be brand dependent. Apparently, going by case weights, neither Federal nor Remington feel it cost effective to have two entirely different sets of case forming dies for a product with the same exterior dimensions. Per the linked article, any difference that might exist is about 1%-or less- of case volume.

 

[DWalt]

And the same is true for the 7.62x51 NATO case. One can find civilian .308 cases which are heavier than military cases. If you have a variety of case headstamps and a scale, you can see that for yourself. On one occasion on a visit to Federal's plant around 2003-04, I personally witnessed Federal making 7.62x51 military cases for shipment to Lake City for loading. They were coming off the same equipment used for making .308 cases, only the headstamp was different. ATK is the parent company of Federal, and also the contract operator for Lake City AAP at that time.

 

[smoothshooter]

Don’t worry about it. Not an issue with factory ammo.
With reloads, if using military cases and commercial loading data, back off the powder charge a half-grain or so.

 

[Warren Sear]

Don’t worry about it. Not an issue with factory ammo.
With reloads, if using military cases and commercial loading data, back off the powder charge a half-grain or so.

Why? The cases are essentially identical.

 

[Mike in Reedley]

Military cases are, generally, thicker. That means less internal space, so higher pressure than the same load in .223.

Our local Big 5 only allows purchasing two boxes (regardless of round count) of the same ammo. Last time I was there I bought two big boxes of 5.56 and two regular boxes of .223. The kid working the counter said it was okay, since they’re different calibers.

 

[DWalt]

Military cases are, generally, thicker. That means less internal space, so higher pressure than the same load in .223.

That's a myth.

 

[Mike in Reedley]

I’ve taken a Win. 5.56 and a Win .223 case and trimmed them to the same length. I filled both level full of 748 and the commercial case held more powder than the military case. My comment (as stated) was a generalization. In my experience, the military case had less internal capacity.

 

[pasound]

If you are worried about compatibility, most new AR clones all say they chamber 5.56 and .223. My S&W M&P15 is noted as chambered for both.