Originally Posted by lbwar15
To skip all the explaining just know 5.56 is a hoter round and a .223 can not handle it. It's the same as .38 and .357 mag.
No, it is NOT
the same thing as a .38 Special and a .357 Magnum. A .357 Magnum has a .100 longer case than a .38 Special. You physically cannot chamber a .357 round in a .38 Special revolver because the round is too long. It was designed that way.
A .223 case is identical
in exterior dimensions to a 5.56 MM case. The only difference is the 5.56 MM case may have thicker case walls at or near the rim. This however is not always the case. Sometimes these internal dimensions vary according to the brass manufacturer.
Another thing is that there are .223 loads listed in many of the older reloading manuals from the early 70's, that have higher pressures
than many of the 5.56 MM Service Rifle loads currently listed in some of the newer, more modern manuals. In this regard all of this, "don't shoot 5.56 MM in a .223" goes right out the window. The only difference in these 2 rounds externally is the freebore in the barrel itself. That is not enough to run chamber pressures higher than some of the early .223 loads I mentioned above, that are listed in the older manuals.
I've run these hotter .223 loads in both .223 and 5.56 MM chambers, in BOTH
.223 and 5.56 MM cases, with no ill effects what so ever. I'm talking tens of thousands of rounds over a period of decades in well over a dozen different rifles. That in itself is why I really wish these "Don't shoot 5.56 MM in a .223 rifle!" threads would simply just go away. In over 40 years of shooting, I have never seen
any .223 chambered rifle that was adversely effected by it, EVER. I no longer even bother to segregate my 5.56 MM and .223 brass anymore. Unless I'm loading match ammunition for guilt edged accuracy. There is no need to do so.