I always thought the pumps on mossbergs rattled too much. It’s really the only flaw on an otherwise perfect shotgun
The rattle of a pump gun is like the rattle of a rattlesnake.
Mossberg claims that is an an intentional feature. They say it increases its tolerance to stress and abuse in the field - ie. I wont break as easy. Dont know if I buy this explanation but thats what they claim. The military buys it though - If it dont rattle it dont go into battle.