what's the difference between needing certain weight (grains) to prevent dry firing your bow and needing the proper spine stifness for accuracy and true arrow flight? i guess what i'm asking is...i shoot Beman Realtree MFX 340's at 10.4 grains per inch. i was told this is about as light as you can go for my bow (76# /w 30" arrows) without dry firing it. so how could i use the same "340" arrows that are that much lighter (2.2 grains per inch) without damaging my bow? correct me if i'm wrong but isn't "340" something to do with the spine and not grains per inch. if this is true than you aren't really gaining anything if you still have to shoot arrows at certain weights. your just shooting stiffer arrows, not "lighter" arrows.