I use a propane torch over a pie pan of water in a darkened room or outside at dusk.
I heat the neck just enough to show the merest hint of color and then drop them into the water. Most of it is just feel-- I'm heating the case until I can feel it get hot between my fingers. If I let it heat enough to burn me, I've probably ruined the case. I also count. The first couple of cases heat up at a count to ten. The next case, I get ready to drop after nine. With the way I heat and the way I count, 11 is usually too much.
After I'm all done, I shake out the brass and put it back on a dry pie pan and bake it in a toaster oven at 300 for 20 minutes-- just enough to evaporate remaining moisture. Alternatively, if the cases are dirty, I'll throw them in corn cob and let them run through the cleaner. The cob removes whatever moisture that remains.
Lead? I don't know how lead got into the discussion. At the solder factory, I was working with alloys of copper, tin, antimony, and silver. We made filler metals for solder, brazing, and welding. While the alloys I made were different than brass (no zinc) the general methods and reasons for annealing were the same. If you wanted to make something more brittle, you beat on it or heated it and let it cool slowly. If you wanted to make something more pliable, you heated it just enough and quenched it quickly.
