I expect the larger bores haven't panned out, due to the necessary charges not being used. At some point, higher velocity of a smaller bore, should drift less, ie: .40 or .45 running 2,200fps compared to a .50 making 1,600fps or 1,700fps? A .69 at 1,500fps should do exceptionally well, if the shooter is up for a bit of punishment. I'll have to run the numbers to see. Now, where's that list of BC's?