One of the guys at my club loaned some of the machine guns that were used in the movies, Rambo and Predator and many others. He was talking about it a few months ago and said they had to rig the actors somehow as they were firing the machine guns because the guns would just spin them right around. At one time this guy had over 1000 machine guns and had his home installed with a burglar alarm that could gas a burglar entered his basement. I have heard several police comment on his house and they were almost afraid of near it on a burglar call.
