Apologize for the ignorance: Is the 28 the Queen of .284's ("commercial") or is it all about powder capacity and twist? You can't kill something "more" dead and after a bit the Earth's rotatation comes in play. Spitballing I'd say if you can't "do it" with an '06 you'd need the STW. Beyond this .50BMG; and rifling: There's a finite point which could be explored in my recent "4 Bore Rifle" post.
BTW IMO "Queen" is better suited than "King" for boats, cars and guns. No specific reason: Like the 16ga:
That is all.