Tim, Gamo is famous for publicizing extremely high feet-per-second claims on their rifles. To be fair, many air gun manufacturers have done so over the years, ever since the "velocity wars" began back in the late '70s according to long-time air gun enthusiasts. Back to Gamo, they stamp the extreme velocity claims for their rifles on the top of the air chambers and that is what you see - "1600 fps velocity with pda platinum". The platinum reference is to a type of lead-free pellet Gamo developed that is very, very light-weight and therefore is shot with an atypically high velocity. That extreme velocity comes at the cost of generally poor accuracy; as a bonus, the gun almost invariably produces a lower velocity than claimed when shot in real-world conditions. I am only guessing on this next part but, I believe your Magnum (the actual model name for your rifle) is a bit older than the current crop on sale and carries an earlier max velocity number. Some manufacturers, including Gamo, continue to monkey with producing extreme velocities using in-lab, non-real-world scenarios and materials to obtain inflated velocities. As a result of this ongoing prestidigitation, the reported velocities continue to climb; what you report is likely just the "march of progress" as Gamo sees it.
