I guess it's a matter of giving the general public some flexibility. You have aluminum inserts(light arrow shafts) so you can speed up the bow by going to 100 gr broadheads or use a 150+ gr and have a heavy hitter that will bones easier and be more stable to and through the deer. I think Excal was thinking that 150 grain broadheads are a more sensible choice. I find no accuracy issue with my lighter arrows.