Shotgun clays work well for me. Ping pong balls glued to golf tees work well also. Bic lighters that ran out of fuel. I used to shot burned out light bulbs in a trash pit at my grandparents house. I did not have to worry about glass. When the pit was full grampa burned what would bun, then covered it over with dirt. (I also used to shoot field rats in that same pit as well.)
No matter how many times you do it and nothing happens it only takes something going wrong one time to kill you.