I used to shoot my 78# bow all the time. Now, my shoulders prefer the 65# bow I most commonly shoot. I ,too, admit that it seems that my lighter weight bows often feel puny. However, I think that is just because we are accustomed to that solid heavy feel. Since the lighter bows will shoot clean through most game animals we are likely to hunt, then logically, they are just as effective as our heavier bows. It is just a sense of feel on our parts that makes them seem less efficient.