Speed is way over rated, but it sells xbows. Your Jag is not now nor ever will hit 310 fps, fwiw. A 175# Excal only hits 305 fps w/ min weight arrows and a diff string. I answered another post of yours advising to watch the weight of your arrow[s]. The big diff will be in the inserts, either alum or brass. I'd cut the 20" down as much as you can go.......I'd also make 30-35 yds the farthest range I'd try a shot on a deer at, but that's me........