The vanes could be part of the problem. Have someone watch you, or video yourself, and try to get an idea of what you are doing differently. If you can group at 15 yds, you should be able to at 20 yds. Concentrate on your release and follow through (bow hand and string hand), and keep your eye on the spot until the arrow impacts. At worst, you may have to limit your hunting shots to 15 yds or less.

Chad