Is annealing necessary? The pressures of .410 are considerably lower than rifle pressures. Gil
I've never reformed brass cases, but I'm a metals nerd, and, from what I've read, when expanding a bottlenecked rifle case into a straight-walled case of larger bore diameter, annealing is necessary to prevent the cartridge from cracking or splitting at the case mouth. Because the simple act of bottlenecking what was originally a straight-walled tube during the case--forming process at the factory, has already work-hardened the brass somewhat. De-bottlenecking it means stretching already-stressed metal. It might not like it without being stress-relieved first.
Nothing to do with the chamber pressures.
I of course invite correction from those who've done it. I'm here to learn.
