Annealing refers to heating the case neck and quickly cooling it in water. This decreases brittleness (from work-hardening--sizing, expanding, etc.). The only time I have found this necessary is when I was forming bottle-necked rifle cases from ones of a different caliber (necking up or down). You don't need to anneal for regular reloading. It is not necessary at all on straight-walled cases, just bottle-necked ones.
|