Bayourambler
Member
I am trying to get a dope card made up for a round that I reload for my 308. By using published bc for the bullet and my chrony numbers, the federal ballistic chart is not close at all. Is this common? My sd numbers on this round run around 14. I guess I will do some test shots at different yardage , and maybe come up with a velocity number to plug on to ballistic calc that makes things closer ? I'm guessing all things being equal, the chronograph is way off. It says the bullets run 2715 fps. According to what the come up was at 375 yds, the only velocity number that worked in the calc. was 2900. Is the chrony that far off!?