BMT - The Bond .410/45 is more fun than should be legal. My grandsons (14 and 9 and both mui macho) love to shoot it.
Best loads -
.45 Colt Gold Dot - accurate.
.410 Winchester 3" 000 5 pellet buckshot - hand size group
at 7 yards and best penetration of the loads I've tried.
I like teh buckshot. As a last ditch wepon, that could be nasty.