When fired from an unsupported position, the pump action rifle, like the semi-auto, has the advantage of firing a subsequent round without breaking the firing grip. But unlike a semi-auto rifle, cycling the pump action from a supported position requires disruption of the position, which is detrimental to hitting the target. As a result of this reality, the competent bolt gun shooter can likely make an accurate follow-up shot, quicker, from a supported position, than someone equally competent with a pump. Perhaps the best anyone could do with a pump is to maintain contact between the support arm and it's platform, be it your leg or the ground, and push the rifle forward with the firing hand, to eject the expended round, then pull it back into the shoulder to chamber the subsequent round. That should be disruptive enough to encourage anyone to buy a gas gun. As for me, I'll stick with a bolt gun.