I have a tempilstick but find it inconvenient to use. The tempilaq, which is a paint you put on the inside of the neck probably works better, but I would also rather not go to that extent.
Brass glows to a dull red in a nearly dark room when it reaches 800 deg. F. That is the temperature you want to get to, and then dump it in the water.
Rather use your fingers, I would suggest a drill and either a Lee holder used for trimming length, or chuck a deep socket in the drill and put the case in that as a holder.