The Girardoni air rifle is my top, too. The gun on the expedition was Meriwether Lewis's personal rifle which he loved, but also understood the propaganda purposes of. A great tragedy of the expedition is that Lewis was so worried that he was going to be forced to pay for all of the IOUs he incurred on behalf of the US government that he sold almost everything from the expedition within around a month of its end. So we don't know what became of his rifle, specifically.
But if it's not a Girardoni air rifle, it would be an
Apache revolver, of course!
