When you fire a semi-auto, the slide blows back to eject the shell and reload the next round. If your wrist is "limp," your hand moves back with the recoil of the gun and the moving slide going in the same direction. As a result, your hand and wrist and arm absorb some of that recoil energy. If you absorb enough, the amount of energy left to move the slide back - which is moving against a spring trying to push it forward, decreases so much that the slide doesn't go all the way back before the spring starts to push it forward again. Under the right conditions, this can happen when the spent shell casing is only halfway out of the chamber, in mid-ejection. So then the slide slams forward and traps the empty shell casing and stops the slide completely. At that point you're screwed - the gun has not reloaded, and the the slide is jammed solid with the empty shell casing sticking halfway out of the chamber.
An excellent summation of the problem.
Thanks you for taking the time to explain it!!!!