I make 6.5x58R Sauer brass from 9.3x72R, 222Rem from 223, 22-204/6mm-204/25-204 from 204 Ruger brass. All have to be annealed. Also when I start getting split necks on cartridges like the 22-250 I anneal the whole batch, I keep batches of 50 separated so I can keep tract of them.
I use an appropriate sized deep socket(brass base just fits in easily) and spin them over a propane torch until the start to color, then tip them out onto a damp towel. The damp towel sucks the heat out of them quickly and then I don't have to worry about drying the brass as in a water bath. You can do a bunch quickly and get right to reloading. I believe having the head of the case down in the deep socket somewhat protects it from the heat of the torch also.
If you want to sure you don't heat the base of the cartridge you can stand them up in a pan of water so just a little more than the area you want to anneal is above the water when I used to do this I would use two torches one on each side of the case. I'd set them in rows and just move down the row heating them one at a time.
