(Not sure what category to put this in, and I've never annealed a case and don't plan to.)
If I want to anneal a piece of steel I would heat it up then let it cool slowly. If I want to harden it I would quench it in oil or water.
If I want a harder bullet I drop it from the mold into water.
If I want softer gas checks I heat them then let them cool slowly inside of a pipe nipple with caps on each end.
Question: So why, when people anneal case mouths, they heat the neck and shoulder then quench the case in a liquid? Seems quenching would harden the case rather than soften it and make it more malleable.
This question has kept me up many a night wondering. (Just kidding)
I'm kidding about this keeping me awake at night, but I have wondered what's so special about brass cases that they soften when you quench them and every other metal hardens when you quench it.
Thanks in advance.