Thanks for the good ideas out there from everyone as far as increasing amount of ammo that is handy.
The first (really inexpensive) trick might be to attach one of those "butt cuffs" or whatever they're called. No screwing or drilling required, just velcro the carrier onto the stock. Hmmmm, more research to do.
I did go with Federal 00 Buck Tactical Load 9-pellet shot and Rottweil Brenneke rifled slugs.
Hope everyone has an excellent July 4th Holiday...
~ Blue Jays ~