Spring and hammer setups tend to run higher LPR pressures to move said hammer, though, which helps to keep bolt fllyback in check.
Then again, I've seen A/T pump setups that you can fire without holding the pump handle, and fire again by pulling hard enough on the trigger to close the bolt. All depends on the particular setup. Generally, pumps won't have that much flyback because there's a lot more mass at the other end of the pump arm than there is on a semi. And you really should be holding the pump handle anyway