5.56mm NATO versus 223 Remington Chamber Differences

[constructor]

Why do people insist on saying "5.56mm NATO chamber," as if all things that were designed to shoot 5.56mm NATO have the same chamber?

The M249 has a difference chamber, and shoots 5.56mm NATO.
The M27 (HK416) has a different chamber and shoots 5.56mm NATO.
The Stoner 63 had a different chamber to the M16, although it was gone by the time 5.56mm NATO came along.
etc
etc.

Because the 5.56 NATO is completely different from a 5.56 CLE, the 5.56 CLE is more like a Rem 223 than a 5.56 NATO, that is just 1 example. Those people that order reamers need to use the exact name of the reamer they want or they may end up with something they don't. Reamer makers and wildcatters can name their design anything they want. Many believe their design will improve upon the old designs and they name them something different because they are different.