I wont drag this out, but I found the perfect targets. Paint ball ammo. 27mm diameter. Brightly colored and they explode when hit. I hit them at 20 meters and it feels good when they pop. Give it a try.
What does a cheep paintball gun cost. My neighbours dogs are driving me crazy, and I don't want to risk shooting them with any of my rifles. (well, not if I'm not going to assasanate them at night with .22 and silencer, and then dump them)
They mutalated my jackrussel in my own yard, as they run free, and I have complained to the neigbours a couple of times now.