The lowdown on 5.56 in a .223 chamber

[skorpion]

A few years old, but a great read!

http://www.luckygunner.com/labs/5-56-vs-223/

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.

In order to create this article, I temporarily set aside all of my previous knowledge and opinions while several months’ worth of new research and experimentation on the topic was undertaken. In addition, extensive discussions with gunsmiths, ballisticians, and laboratory technicians were conducted.

[imanaknut]

So if I read the article correctly, and with all the actual as well as anecdotal evidence he does get confusing, in the end his recommendation is what we have been saying all along. .223 out of everything is ok, but he does seem to warn against 5.56 NATO in a .223 barrel.

Also for those not too familiar, it is the barrel marking that is important. I have a rifle that the receiver is stamped .223 but the barrel is stamped 5.56 NATO.

Duh....

[FunkyPertwee]

So if I read the article correctly, and with all the actual as well as anecdotal evidence he does get confusing, in the end his recommendation is what we have been saying all along. .223 out of everything is ok, but he does seem to warn against 5.56 NATO in a .223 barrel.

Also for those not too familiar, it is the barrel marking that is important. I have a rifle that the receiver is stamped .223 but the barrel is stamped 5.56 NATO.

Duh....

Lots of imported rifles are marked .223 when they are actually 5.56. SAR-3 for example.

[skorpion]

About 11 or so years ago I shot a bunch of M193 5.56 through a .223 chambered 20" heavy-barreled AR (my first AR15) and had bad results. This was before I realized that probably wasn't a good idea - the internals began showing signs of excessive pressure. The base of the firing pin was mushroomed, the disconnector was dented from the hammer hitting it too hard, and the FCG pins kept working their way out.