In an ongoing quest to learn more about converting 9.3 X 74R brass to 3" .410 brass I am wanting some info about annealing the top third of the case. It seems to be pretty much a given that the top third of the case should be annealed before allowing fire forming to expand the neck to .410 chamber dims. After reading up on doing it, and seeing everything used from a $1300 electric induction annealer to a handheld propane torch, I'm left with a question about the process. I see conflicting methods concerning the cooling of the brass after the heating. Some dunk them individually, and immediately, in water. Benchrest shooters, who use the expensive annealer I mentioned above, seem to let the case cool on it's own (in the videos I watched).
I've always been told that to properly anneal an action, or any other piece of steel, it should cool as slowly as possible. Some used to even pack them in lime to extend the cooling down period. Is brass different? If the idea is to relieve internal stresses in the case shoulder and neck, and result in maximum ductility, wouldn't a slower cool down be better than a quick dunk in water?
