Anyone can fire a machine gun from the hip using one hand. Also, when firing anti-tank rockets, there is no such thing as a back blast area unless you are trying to attack the hero.
Wait a minute here - you've directed some of those *extreme hero* movies, haven't you? :)
Well there was that LAW in "The Enforcer" where Tyne Daily just about got cooked by the back blast during the demo of the LAW, when Dirty Harry pushes her aside at the last minute. Funny, I can' recall why they were demo-ing the LAW to the police? Oh yea, now I remember, the bad guys had stolen a bunch of them. I think. :)