Rack hit the nail on the head on this one . Spine is very critical in getting good arrow flight , with field tips , then when you add " wings" to the front of the arrow with a broadhead it becomes all the more critical . In our quest for a fast arrow alot of us go for one with a marginal week spine , where we should be going for one with a stiffer spine , say one rated for 10 pounds heaveyer . I' ve found that its easyer to tune a broadhead equiped arrow that is slightly stiff as compared to one that is slightly weak . Another thing to consider is fletching , 3 or 4 , 4 or 5 inch feathers or vanes should be minimum , the bigger the surface area up front = the bigger the surface area in back , the point being I dont think you want to use a big 3 or 4 blade broadhead up front with 3-3 inch strait fletched vanes .