A rimless .44 magnum might be an interesting idea if our gun laws weren't so restrictive towards small semi-automatic rifles, although a pump action might be interesting. But rather than a cut off .308, why not use it full length, or cut off .30/06, to provide a bit more powder capacity, and marry it to a 760? Even SC could appreciate that. It wouldn't do anything a .444 Marlin wouldn't do as well, but it would feed better from a box magazine, and the 760 is quicker and stronger than a Marlin, and slimmer than a bolt gun.