""So, Don, you are saying that if Bobert was on top of me, beating the crap out of me, I would have no problem pushing him off before he could hurt me? I have a few pounds on him...""
No BB! I'm saying that you would be capable of rolling and throwing him off before he could begin to beat you to a pulp!
And so could Zimmerman if he hadn't been so intent on reaching for old Betsy!
In the UK, I wouldn't have to worry about getting a gun out of my pocket (since they are rightly illegal), so whoever was on top of me would be leaving PDQ, and probably singing soprano for a week, unless he outweighed me by a considerable margin.