[CurlyDave]

I’d add that those 5.56 cases are annealed to harden the neck and “leade.”

Annealing actually softens the case. Allowing it to expand slightly and seal the chamber better.

.223 cases are usually annealed also, but are polished after annealing to produce a more appealing cosmetic finish. NATO specification requires visual proof of annealing which is why they are not polished.

It is not possible to anneal the "leade" which is a dimension and not a piece of material.

[Gaffer]

The part that makes up the leade dimension is longer. Look at th SAAMI drawings of a he cases.