A double-barreled shotgun has only two rounds. After that you are SOL. You need at least a Mossberg 500 with an extended magazine tube.
I’m well aware of the advantages of a pump shotgun but most novices fumble-bobble-mishandle-forget something in the operation of a weapon when it is pulled from a dusty closet. This man was a complete novice so it follows to start with the simple.