I use time and feel to gage proper annealing. I use a simple propane torch and hold the case neck in the flame with my thumb and fore finger holding the base of the case, rotating it back and forth about 180 degrees while counting to ten. If it gets hotter than normal I will drop it in the water early or if it does not get as hot I hold it a bit longer but normally it goes in the water at the ten count.
Tim