At an outdoor range, set up a board of appropriate size and hang 16 clay pigeons on it in two rows of eight.
Take two people with 10-shot .22 LR rifles, and at the buzzer they race to see who can get their 8 birds off the board first. Obviously, take care to ensure that everyone stays safe; but other than that it’s a fast, fun, and entertain way to burn up some cheap .22 ammo.
