I'm getting into this a little late but, when I carry my extended mag shotgun(870) this is what I do. I keep four Federal Tac 00 buck in the tube. In my sidesaddle I keep three more tac buck along with three Tac slugs. Havng only 4 shells in the tube allows you to instantly insert two slugs if the situation requires it. I also have the Choate orange follower. It keeps the spring uniform and allows for immediate recognition of an empty tube.