A number of years ago, a neighbor's 12 year old son got ahold of his .22 rifle on Saturday morning when daddy wasn't home.
The kid fired a .22LR at a bird, in flight. The bullet punched through the siding on the house next to me, and continued through the insulation and inside drywall. It then crossed through the kitchen, went through an inside wall (total of 2 layers of drywall) and finally embedded in the drywall at the far side of the living room.
Fortunately, no one was home.