My suspicion would be that, just like advertising today, the original velocity claims were “enhanced” a bit (or rounded up).
Come on Mike, I really believe the 300 yard leaf, 400 yard leaf and 500 yard leaf on my .450 NE were used a lot in the old days for accurate game sniping. They weren't there for marketing PR at all.
Quote:
With these wonderful old rifles so much is now just mystery that is lost to the mists of time. - Mike