Im guessing this is a percussion rendition of Ashleys “super hawken” he had jake and sam make him around 1823 to keep the natives off his keelboats. His was supposed to throw a 1 oz ball from a barrel 3 1/2 feet long. I think Baird had one made in .69 caliber as that is what the US issue was at the time and a .69 caliber ball is close to that 430gr/1oz mark. Looks like a dandy elk rifle.
A .69 calibre ball, if 15 bore at .677" weighs 467gr. A .682" ball that I use in my .69, weighs 482gr. An actual 14 bore (.693") ball weighs 500gr.
A .622" ball weighs 437.5gr. = 1 ounce. A .650" ball is 17bore and weighs 412gr., rounded up from 411.76.
These are indeed, good elk and moose rifles. They will also quite handily kill deer and bears - and squirrels, but "Heavens, such a bore is rather large for squirrels in one desires their flesh, for fare".
Old joke about Baird's .69, from "The Primitive Rifleman".