ORIGINAL: bigbulls
You gotta hold on to it so that the gun has something to recoil against. If you're not holding the gun tight into your shoulder it allows the entire fgun to move rearward at the shot. Ifthe entire gun is moving rearward while the bolt is trying to cycle rearwardthe boltwon't make it all the way back and will "short stroke" itself, not eject, and not pick up the next round.
That makes sense, alright! But while I can see how this would be the case with a recoil-operated weapon like the Browning Auto Five, it should not be necessary in a GAS-OPERATED rifle like the M1, M14, or Remington semi's!