I thought this might be a fun twist on gun selection... Instead of picking "the best caliber for deer", or "the best antelope rifle", I'll lay out a situation, and you pick your ideal rifle for those conditions.
To avoid a pisssin' contest, let's all just assume the shooter is someone who practices often and can make the shot presented.
Situation:
Quarry: Bull Elk (let's shoot for the moon and say he's 380"+)
Animal's demeanor: feeding & calm
Animals orientation: ever so slightly quartering towards you
Terrain: Open sage country (assume you can't get closer)
Distance: 510 yards
Shooter position/rest: Prone across the hunters back pack
Shooter demeanor: Calm as one could be when shooting at a 380" bull
Wind: little to no wind, assume 0-5 mph
Temperature: 30 degrees Fahrenheit
Other weather notes: No snow, but the weather man says that it will (they're never right... or are they?).
Well, there you have it... I have my own opinion, but let's hear which gun/ammo combo you would you want in this situation...