IL BOW MAN, Im no expert but look at this. A 390gr arrow shot at 250 fps will deliver 54 ft lbs of KE. Increase the weight of the arrow to 400 shoot at the same speed will bring you KE up to 55 ft lbs. Now take the same 390gr arrow and increase your speed to 260 fps and you will get 58 ft lbs of KE. Its not all about arrow weight. Don' t forget velocity gives a fair return to your KE. Just some food for thought.