The reason that there is so much misinformation about the subject is that misinformed people like yourself keep adding their tripe to the pile.
Cartridge shell cases are not annealed to harden the neck. Just the opposite! Neck annealing is done to eliminate residual stresses in the neck and shoulder so that stress corrosion cracking will not occur over time. The annealing process actually softens and weakens the neck.
Most all rifle bottle neck shell cases are neck annealed which discolors the mouth and shoulder in the process.
Commercial ammunition manufactures typically removed the discoloration with a vigorous wash to make the shell case bright and shiny. Military shell cases are required to leave the discoloration to visually prove that the shell cases were in fact annealed. The "leade" in in the firearm chamber and nothing done to the shell case affects to rifle.
Please do not post misinformation on this forum.
Okay. I agree on the annealing, but there is a difference in the overall length. Take a look at the SAAMI diagrams. Likewise this will affect headspace.
Actually, annealing softens the brass so that working the brass when sizing the case won’t cause cracking. That’s what creates a discoloration of the cases.