I got my first compound bow a few months ago. I had my local bow shop set it up and they told me what arrow to get for my draw length (29") and draw weight (70lb) and that was a Easton ST Excel 340. Since then we have backed my draw weight down to 60lb. I downloaded Easton Shaft Selector 2011 software and according to that I should be shooting 400 grain arrow and now a 340. I did change the software to match the beginning setup and it does show a 340. My question is should I purchase 400 grain arrows now?