I like 22 LR rifles and pistols. My sons and I will play a game like HORSE where we pick a target (old soda cans with water are fun), a distance (anything with a safe backdrop will do) and a shooting position. If the chooser makes the shot, everyone else has to follow or they get a letter.
I'll also float clay skeet out on the pond. Those are fun to shoot and sink. I just make sure I get the kind that are supposed to dissolve - but not too fast.
All the talk about how deadly ammunition needs to be is too dark for me. Killing cans is what I like to do.