For open sights, I recommend the Marine Corps "A" target, it is used out to 300 meters on the Known distance qualification course. Make your own with these specs: Target size is 6'0" tall X 4'0" wide. Bullseye(black)is 12", next ring is 24" and third ring is 36". This leaves a lot of paper so the actual size of the target only has to be the size of the largest outer ring and there is a 'V' or 'X' ring dead center of the target in the bullseye about the size of a half dollar. The link below will show all three KD targets used out to 500 meters, with specs, look near the bottom for the correct pic. I can't get the previously posted link to work. If you want to get the target specs, you will have to go to
webshots.comand then search for <DNA Auto Repair> to find my album. I only have two pages, it's on the bottom of number two IIRC.