RCBS hand primer, sitting in my easy chair with two boxen of brass; one sized and unprimed, one primed. Have my primer tray half full, chucking out about 20 rounds a minute. The wife comes up to tell me about something and my attention is taken away for just a moment. Now I've got a ringing in my right ear and a nice burn blister on my shell-loading hand. Double fed the case and the two primers fired off. Ow. Focus on your task. My 5 year old doesn't bother me when I'm at my reloading table unless I have him help me out by request. My wife won't be anymore either.