Bow is 50lbs at my draw. One arrow is 420gns at 180fps. Two arrow is 715gns at 141fps. Light arrow is full length and heavy is 29 in. With differance in length , my gap is almost the same to about 18 yards . most of my shots are within that range. Light arrow has 125gns up front. heavy arrow has 300 up front. penetration on my block is about the same. past 20yds the heavy really falls off. as I said I rarely shoot past 18. So , what do you phisics guys think about this ? momentom, KE? Which is the best? I'm thinking about deer hunting with the light and hogs with the heavy. What say you folks in the know?