i don't quite get that. w/ a chrono at pt blank we're dealing w/ an initial velocity - plain and simple right? the only acceleration we're dealing with is caused be gravity.by the timethe arrow is in the chrono there is no more horizontal acceleration. i don't believe it matters what the bow did, or if the arrows were thrown - i think bg's right - its harder to slow mine down. we're both shooting 29" draw, and our pounds were w/in 2. he had 4" fletchings on a slight offset and i had 2" blazers w/ helical and so offset the vanes are just barely on the shaft - and they won't quite get thru the nap 360 w/out one of the bases touching the launcher. (i over did it just a little.)