Funny how people make it out to be such an issue you would think there was thousands of .223's in the scrap metal pile cause 5.56 ammo blew them to smitherines.....
Well where they at?????? Yeah I thought so.
I've fired at least 250,000 rounds of 5.56mm ammo in my .223 rifles since 1968. All my guns are still working.
Strange that SAAMI came out with their dire warning about the time millions of 5.56mm cartridges hit the market. In this lawyer run society few gunmakers, gun writers, panjandrums or experts are going to say SAAMI is wrong.
There are a number of different .223/5.56mm chambers, at least one dozen of them. A gunsmith tells me no US maker he is aware of chambers guns using a SAAMI spec reamer. .223/5.56mm rifles have become wildly popular.
For most shooters there is no way of knowing for sure what kind of chamber the gun has. It could be a very tight chamber or a huge sloppy one. Some companies regrind their reamers. Most of the those rifle barrels are not chambered by machinists or skilled technicians. Theres a race to the bottom in salaries: Unskilled labor does much of that work. i've seen out of round chambers, off center chambers and bulged chambers(in NEF guns).
i'm not telling anyone what to shoot in the chamber of his/her gun. i've saved oodles of money by using surplus 5.56 ammo in my guns. I'm an EOD guy; much of it was free.
Until recently very few had pressure tested 5.56mm ammo fired in .223 chambers. What you have been told may not be true.