Didn't the .351 come chambered in a slide action rifle of some sort? I always thought that a light, flat, modern slide action carbine size rifle would be the berries for a lot of applications. I have always thought that pump shotguns and slide action .22s have a lot to recommend them. I know I can get back on target faster with a pump than with a lever, bolt, or even a semi auto. Make it manufacturable with modern CNC equipment, throw in some good features such as interchangeable magazines, swappable barrels, ambidextrous use (bottom eject, reversible safety, etc.) and you might have a winner. The .350 Legend would work good in something like this.