doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com English game loads data 2 1/2" shells.

Not sure about the BS in the difference between true MV and measured 3 foot velocity, Jones. The velocity figures in John Taylor's "Shotshells and Ballistics" come from the shotshell manufacturers themselves. And numerous shotshell companies, both American and foreign, are represented. The difference between the two figures is pretty consistent at around 100 fps, give or take a little in either direction. And it makes sense to me that pellets will slow down quite a bit shortly after their initial exit from the bore, because they're no longer being pushed by the burning gas from powder, and encountering more resistance from the air.

As for terminology, muzzle velocity in anything written by an American writer is assumed to be that measured at 3 feet, not at the muzzle--unless specified that it's true muzzle velocity. The measured 3 foot velocity is the only number SAAMI lists in its official charts for shotshell loads.