just starting to get into it now. just bought a grain scale. I was amazed at the gtg, when several of us did some comparison shooting w/a chrono. I was surprised as how an arrow 40 grains less, flew 40 fps faster. Also found that my 100 gr. field tips were actually a little over, 108. 104 etc. my muzzys all on @ 100gr. Just another step for obsessomg.