Atlasman, you could not be more correct. And I truly regret both my son' s and my experience. I don' t know how to calculate kinetic energy but would like to learn. Don' t know the grain weight of my arrow (seems like for a guy who' s bow hunted successfully for a few decades there' s quite a bit I don' t know), but it' s a 28 3/4" 2413 XX78. Any suggestions would be welcome.