After twisting his hand around and breaking his wrist, take the gun and point it toward him. Then follow through with your fingers in his eyes all the way to the ground, and follow through by jamming your knee into his testicles. After this is complete, is possible, follow through by punching his testicles.
This is part of a larger orientation/training film that was directed by John Ford (The Searchers, Stagecoach) as part of his work for the Field Photography Unit. Fairbairn was almost 60 when this was filmed.