Brass is an excellent conductor. It gets hot very quickly and cools very quickly when it hits the water. It is within a few degrees of the water temperate within seconds of being submersed.
I have dropped an annealed case in the water and immediately reached in and picked it up by the neck. It MIGHT be luke warm if you're quick.
I've also annealed brass, drained the water, shaken the brass around in a towel and gone to immediately size it. I've never had a problem.
Still happily answering to the call-sign Peetza.
You do not HAVE a soul. You ARE a soul. You HAVE a body.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.