Most of my case annealing has been limited to .45 Colt, mostly just to prevent gas blowby. In this I have been very successful, and I've gotten the added benefit of longer case life before mouth splits. I recently endeavered to apply the same process to about 200 pieces of .30 Carbine brass due to unknown number of previous firings/reloadings. My process involves one of the common methods employed--that of an automotive socket close to the case diameter that is chucked into a drill by means of a bolt secured through the hole in the back of the socket. I anneal in a very dark room (I have to wait until my eyes adjust before I can even see the cases). I spin the case mouth in the hottest part of a propane flame until I see the case mouth just start to turn red. It took an average of 6 seconds in the flame to reach this point with the .30 Carbine brass. Then I immediately point the socket down, letting the case fall into a bucket of cold water. I usually do this to squeaky-clean polished brass. This time, I just cleaned the brass well in hot detergent water followed by some cleaning with lemishine water. This left the cases clean but a little tarnished--more of a dark golden color.
Anyway, I was alarmed after dying the cases and seeing that while the case neck was brass colored, and there was a definite line of demarcation where that supposed annealing stopped, the rest of the case had turned blue/purple--all the way down through the case head. I can't imagine that the case head got anywhere near hot enough to be annealed too, but the blue/purple color has me concerned. How do these look? Did I just ruin 200 pieces of brass?