What I was getting at is that you need to be far enough back to get the seperation of the groups. Even if you shoot basketball sized groups at 20/25 yds its easier to tell that the one group is left/right/up/down from the other. At 15 yds and under the groups may overlap too much to get clear results. Also shoot both sets of arrows 3 or 4 times and compare your groups before making any changes to get a true idea of how your shafts are impacting. When I start checking broadheads against field points I will really back up to 30 or more to check my group, usually 2 fieldpoints then a broadhead, 2 fp and 1 bh, 2fp and 1 bh. Then if the 3 broadheads are mixed in the center of the other 6 arrows I know my setup is on. If its off its easier to see even if its a 20 inch group.