.223 vs 5.56?

[Rumpelhardt]

From what I gather from my limited reading the problems may start when you have a .223 chamber that has a throat that is at the shortest end of the accepted tolerances and 5.56 ammo that is at the longest.
Chambering the round when this condition exists is supposed to crimp the mouth of the case into the bullet so it can’t open properly to release the bullet significantly raising pressure possibly dangerously so.