I use a standard 100 yard target with about an 8" black. This works just fine with most post-type iron sights, and for 200 and 300 yards, I use the appropriate full-bore match targets with correspondingly larger black centres. This allows me two groups on each target, holding centre for the first and 6'o'clock for the second. You must note the group for the 6 o'clock hold will centre below the bull due to the white line between bull and post, or whereever and however you hold.
; For sighting using beads, I use the 200 yard target for 100 yards and 300 yard target for 200. I sight beads to hit in the middle of the bead. When holding a bead 6 o'clock, the centre of impact will be well below the black due to the centre of the bead being well below the black - all dependent on where and how the rifle is sighted, of course.