I was watching Harry Lorayne's Ambitious Card Routine and I believe he starts off the routine with a classic force behind his back. I never considered using the classic force in this way, so out of curiosity, I decided to test it out on a spectator, and was shocked to find the force successful. This is something I'll definitely try to fine tune with other spectators, and I was wondering if any of you other magicians utilize the classic force while it's behind your back? It seems pretty uncommon and I feel it's insanely powerful. Maybe this is common and I'm not immersed in the magic community.