5.56x45 or .223?

Someone posed a question earlier that I could not find...

The question was regarding the interchangeability of the 5.56 NATO with the .223 Rem.

I don't have either, but thought they were interchangeable - one being the military designation, and the other the civilian.

I did think that one might be loaded to higher pressures, but didn't know which.

I overheard a gunsmith the other day about this question, and I asked him further on the matter.

According to this gentleman, anything labeled "5.56..." can fire the .223, but not vice-versa. He said the case on the 5.56 is very slightly longer than the .223, and the 5.56 is loaded to higher pressures than the .223.

Hope this helps and clarifies

5.56x45 is the same as .223(civilian nomenclature)
7.62x51 is the same as .308
7.62x63 is the same as .30-06

The ammo is interchangeable.

Here ya go.

www.thegunzone.com...


Roper

Ok, on the .223 issue I'll agree there are some distinctions. Of course the majority of rifles chambered in that caliber are military styled rifles which would be able to use either safely. It's similar to rifles chambered in
.45-70. Old style rifles are limited to the early spec loadings, while modern style rifles can use the higher pressure loads. Same with some .45 Long Colt revolvers. An old style needs to low pressure to operate safely, but in something like a Ruger, Freedom Arms, etc...you can safely use much higher pressure loads.

My Rock River lower has 5.56 on it. On some of the kit companies they tell you to pick 5.56 or .223.

I think 5.56 is a thicker wall case than the .223. Now, in my Lymam and Speer reloading manuals there is no difference.

Roper

Originally posted by GT100FV
Ok, on the .223 issue I'll agree there are some distinctions. Of course the majority of rifles chambered in that caliber are military styled rifles which would be able to use either safely.

I think the concern is using 5.56 in a hunting/sporting rifle, like a Ruger M77 or Remington Model 700.

Now that I know, if I ever get an AR type, Mini-14 or sporter in .223, I'll keep this in mind.