I've never had a cat with quite this temper.

I did have a cat who could be rather foul tempered though. I finally picked up on her signal that if I was petting her and she twitched just one of her ears by as much as a single millimeter, then I was to imediately stop petting her.

Could Sam be sending really subtle signals?

If not, could he be needing to release some of his energy with some cat toys or scratch post? I know that I sometimes see Sidney just wail on his scratch post - and I'm sure glad it's the post and not me! (but he, fortunately, is a sweetie that wouldn't hurt me)

This sure sounds like an interesting problem. I look forward to seeing other peoples' input.