.223 and 5.56mm incompatability

This is not a new subject and I know that a lot of you have been aware of it for some time but I recently found this link and thought I would give it an airing.
Here in the UK lots of shooters regard mil-surp 5.56mm ammo to be cheap fodder for their .223 target / hunting rifles.

.223 is probably the fastest growing calibre in UK judging by the number of rifles offered for sale, reviews etc



Not to argue with the experts, but having fired many thousands of rounds of “surplus” ammo thorugh a variety of semi and select fire .223s/5.56s, I never had a problem with the ammo or the guns. No doubt the differences in chambers are a factor in the accuracy department, but realistically, with modern weapons, the differences are nominal. Not to belittle the article, but alarmists and lawyers are really stretching it on this point.

And all this time I thought you UK folks were regulated out of the shooting sports. Glad to hear it ain’t so.

I met an “expert” once.

An old boy that bought and sold mostly junk ammo at a Dallas gun show assured Pete Davis and I that he had “all four-hunnert-an-forty known calibers.”

This was back in the heyday of our mail-out catalog, when my database of “known calibers” was over at least 2,000. And it’s grown some since.

Pete looked at him, and in an absolute serious voice, said “Ah, that must make you an expert!” “Yeah, I guess I am!” he cheerfully replied.

All 440 known calibers…my definition of an “expert” ever since.

On the website it shows the SAAMI table for Unsafe Arms and Ammunition Combinations. One of the cartridges listed as incompatible with the .223 Remington is .30 Cabine! Anyone stupid enough to try this deserves all they get, and anyone who that is not obviously an “unsafe combination” to probably shouldn’t have access to firearms and ammunition anyway.

The whole .223 / 5.56 incompatibility thing is only relevant in two ways as far as I am concerned:

1st: If the weapon in question is rather old, like Vietnam-era hardware in either caliber which back then, some of those guns had a variety of issues with their proper functioning which might make a difference in the incompatibility area.

2nd: If you have a fully-automatic weapon and are using 5.56 in a .223 weapon or visa-versa, then the high rate with those differing chamber pressures can cause more FTE’s maybe, or cause more chamber wear.

Not really a big deal with all of the modern weapons today from makers like Bushmaster, Rock River arms, Stag arms, etc… since all of the people buying these are buying semi-autos and will probably never fire enough rounds through the gun to appreciate any issues with the incompatibility. I own an after market M4 in .223, and I’ve fired maybe 700rds of 5.56 R.O.R.G. M855 through it in 4 years, and never noticed a problem. If I were a match shooter with a bolt action in either caliber though, I would definitely want to stick with the exact right caliber since those types of guns are very fine tuned, and might notice a difference.