Geez 1500 yards? That's 4,500 feet! Might as well make it a mile. What's another 770 feet? Pretty soon you'll be using light artillery or a surface to air missile.

To the point: I have a 7mm RUM with 26" barrel. 150 gr Scirroco's go over 500 bc's and are launched at 3500 fps muzzle velocity. Why wouldn't that work for Prarie Boy? Kick's manageable too.