guys im having a hard time finding enough info on how to figure out the wieght of your arrow.. ive done many searches and still cant really get the hang of it. Im shooting 28.5" Carbon express piledriver hunters at 11.3 grains per inch. they have the original predator vains on them and also the bulldogg nock collars.. no wraps or anything like that and im going to be shooting 100 grain tips.. any help would be great!!