I use the propane torch , hold case between thumb and forefinger , rotate case and heat neck area over a pan of water , when the case gets hot you drop it ... you will not over heat too many cases because your instincts to let go of a hot object kick in and you can't over ride that .
I used this on some hard 41 magnum cases I wanted to anneal to load some 41 Special loads in without the cases getting all blackened and it help extend the case life of the lead boolt loads .
Gary