Hey Bassman, I'm no expert but my take on it is (in a nut shell)the BH of your choice is going to fly differantly than the fieldpoints you are shooting/practicing with because of the differance in shape and design. FT being a pointed cylindershaped piece of metalthat is similar in size (dia.) as your arrow shaft, thus norecognizable resistance/defiation in flightcausedby cross wind or trajectory losswhenshooting a variety of distances. Everything is fine at this point because you have tuned your bow shooting the shaft of your choice witha certaintype and weight of field point. All you have to do is take a look at the BH you choose and you'll see (IMO) that there is definately going to be some arodynamic differances because of the BH blades.And, if you choose to use a differant weight for some particular reason (KE?) that also changes things. I think that is why some of the mechanical BH's arepopular with some folks becauseit's advertisedthat you can screw one on and it will shoot justlike your FP with out having to go through the whole tuningprocess again. Maybe we should be saying "re-tune your bow" instead of saying we have to tune the broadheads. Well friend, that's my nutshell for today. Good luck ????.