5.56 versus .223

This is probably more information than you are really want to know—unless you are a gun geek. 5.56 vs .223 – What You Know May Be Wrong

The differences between .223 Remington and 5.56mm NATO have been hashed out many times on the internet. Unfortunately, many of the “facts” that are often thrown around are simply what someone has heard from someone else, leading to a lot of misinformation being accepted as gospel.

My findings, and the opinions of many experts in the industry who deal with the topic every day, were not exactly what some might expect. In fact, many of them had already discovered what I am reporting, although my research was conducted independently.

I liked it.

4 thoughts on “5.56 versus .223

  1. I’ve never given the subject much weight. First and foremost; any two guns, even of the same make and model, may exhibit different pressure and velocity with the exact same ammunition. They stress the hell out of this in every reloading manual. Manufacturers have changed their chamber dimensions over the years within the same caliber designations (my 30-30 chamber is different form the same manufacturer’s 30-30s of several decades ago and it effects which published loads I can use), and again, individual variations occur as a regular feature of having manufacturing tolerances. That and I have at least one rifle that indicates on the reveiver, “caliber; .223 Rem/5.56 NATO”. so…meh. And yes; the brass itself can be different internally– they tell you that in the loading manuals too, but then again I always assume that the brass from one maker may be different from the brass of another maker, regardless of caliber.

    I suppose that one should read their rifle’s owner’s manual. I haven’t seen it; Does any owner’s manual warn you against using 5.56 in their “.223” rifle?

  2. Ruger has expressly designed their rifles to accomodate 5.56mm ammo, indeed, Lyle.

    I did read an AR 15 manufacturers website some years ago, which one escapes me, that their “match” barrels were .223 Remington chambered as opposed to their non-match barrels. And that page recommended against 5.56mm for their “match” barrels. I only remember it because I was sorting out an issue with a neighbor’s AR 15 of that brand that kept popping primers with a batch of 5.56mm ammo of some kind. My recollection was that just to piss me off the manufacturer marked that “match” barrel as “5.56”.

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