I used to shoot in my old back garden, using a neighbour's pre-fab concrete garage as the backstop at about a 20 yard distance...until I missed the boss. A normal aluminium arrow, shot from a 30# bow, travelled 6 inches through his concrete wall. It wrecked the arrow, but fortunately, there was no-one and nothing in the garage at the time. That was the last time I shot not at the club.