What is the recommended maximum temperature in the oven-drying method?
I am afraid I may have done a dumb newbie thing. I decapped and ultrasonically cleaned 150 cases. In the past, waiting for them to air dry took a long time (days), so I put them on a cookie sheet in my wife's electric convection oven. I set the temp at 350, figured I would read a book and keep an eye on them (thru the oven door window) for about half an hour.
After 20 minutes, there was a flash and "poof' inside the oven. Some combustible survived 60 minutes in the ultrasonic cleaner! (This is probably irrelevant, but it happened, and it was an interesting moment. Didn't tell the wife.)
I turned the oven off, and let them cool in the oven overnight. When I took them out, the cases were all 'blued' looking, sort of a strong case coloring in blue effect, with a matte surface texture. I told an experienced shooter at the club about this, and he said I have probably ruined the brass, got it too hot, and made it soft. Particles could come off in the chamber? He said he would not use it. If so, this is an expensive lesson, it is Lapua brass, either once or twice fired. So that is my real question, have I damaged the brass? Any comments or suggestions?