I have briefly searched online for the targets used at Revere's Riders events and haven't had any luck. We are going to the event tomorrow, but I was thinking about ordering some for practice at the house. Is my Google-FU broken?
They have a variety of targets and leave it up to the event director to choose. Personally I've been using standard circle Bulls for south facing ranges and "tax stamps" for north facing ranges. All targets have the same area per scaled distance.