Originally Posted by PetahW
If you're benchresting a pump shotgun with the bare/unsupported forend resting on the front rest, the body's natural reaction to the recoil of a fired shot (forward/against) would be plenty of travel to run the barrel/action forward past the stationary/planted forend (extracting & ejecting), driven by the shooter's shoulder - then when the recoil's over & the body returns backwards to normal position (pulled back by the shooter's tightly-grasping trigger hand), dragging the barrel/action with it, the next round would then be lifted & chambered as the gun passes over the still stationary forend.
All of the above can easily occur in those few tenth's of a second of recoil duration.
Shotguns, especially pumpguns, should not be benchrested, w/o a human body part between any part of the gun & a rest.
I must say, I've never seen that come close to happening. I shot an 870 off a rest before every deer season for years. I never had the action unlock.
Physics would seem to dictate just the opposite, in fact. Since the forearm is steady and the action is sliding backwards under recoil, it would be the same as holding the action and pushing the forearm FORWARD. In order to reload the gun, the shooter would have to go back under recoil and then forward several inches, without the forearm sliding in the rest, and then backwards again. That's certainly not a motion that any normal shooter would accomplish due to recoil.