Ok I have been doing some thinking and calculating using this site- http://bucklemke.com/ke/ke.php
Using my bow and arrow specs IBO-315 DL-29" DW-72# Weight on string-30gr
Arrow 1 Radial X-Weave STL Hunter 390gr KE=70.85
Arrow 2 Aluminum XX75 2219 625gr KE=59.48
Now I always thought that a heavier arrow carried more KE why then is the 625gr aluminum arrow carry 11.37 less pounds of energy than the 390gr carbon? Anyone have any info on this is the site calculator wrong or what? Thanks guys for all the help. When I get the chance I am going to get some plywood and do some experimenting.