I don't know, I honestly don't think it's possible to break your shoulder with the M16's recoil. There was a pretty scrawny guy in my platoon and he came out just fine (And I'm saying really scrawny, like when we had to fireman lift each other, he had problems finding a partner because he was just too light). I guess you could bruise your shoulder if you don't brace it properly, or you could just feel some soreness after firing a few magazines, but that's about it.

Yup, going off to continue studying. Going to be challenging after two years of not using my brain all that much.