All bottle neck cases are annealed at the factory so that the brass does not later split in the neck area while in storage. The neck is worked hardened when formed.
The cases move down a conveyor belt, standing on end, like bottles in a bottling plant. They pass by a number of gas burner flames that heat the neck. The number of lit jets determines how much heat the necks get. 22 Hornet gets less than a 458 mag.
Commercial brass is acid washed after annealing to make in nice and shiny, so you can no longer see the annealing marks.
Military don't care how the brass looks, but they do care a lot that the cases are annealed because otherwise their ammo won't survive storage - and military ammo is expected to stay in storage for 10-20 years before being used. For this reason the necks of military cases are not washed. they want to be able to see that they have been annealed.
Canadian IVI brass in 5.56 recently had the 5.56 neck anneal changed to anneal a bit more of the neck because the brass was splitting when used at high ambient temps (sandbox).
ty for the quick response.
