I'd not recommend a bi-pod mounted to the barrel for a Remington pump. Get him a "Trigger stick" instead. Not the single post one, at least the two legged one or, better yet, tripod post one. Have him shoot with the forearm, not the barrel, rested in the yoke. You don't want to put inconsistent upward pressure on the barrel. BTDT.

'Tis far better to walk alone than to follow a crowd going the wrong way.