Ok I am fixing to build some new arrows but I want to play with numbers first, I currently shoot a commander with a29"DL @ 70lb. with a arrow that weighs 382gr @ 292fps. What I am looking to figure out is there a formula or calculator that will allow me to change the arrows weight and give me an pretty accurate velocity out of the same bow (without building a half dozen arrows, like I did last time I did this 6 yearws ago). Your help is greatly appreciated. For example what would that setup shoot at X gr of arrow weight....Follow me???