Originally Posted By: eneranch
I imagine this would only be applicable if you have a Firearm chambered for 5.56 NATO, not 223 REM.

Here are the SAAMI Specs

Here is a good write-up about the difference

5.56 NATO vs. 223 REM

And what does any of this silliness have to do with a 6x45?
“It isn't so much that liberals are ignorant. It's just that they know so many things that aren't so.”
- Ronald Reagan