I recently aquired a factory Remington 700, in .300RUM. I'm pretty new to the world of benchrest shooting, actually my benchrest career consists of shooting one 100yd shoot in Tomball, and a 300 yard .22 caliber shoot put on by the Dukes (Little Creek Rifles) in Utopia. I shot in the factory class at both shoots. My goal is to end up with something to shoot at 600-1000 yards. So what do I do with this rifle? Should I leave it the way it is? Re-chamber it? Or just buy a custom action and have a 1000 yard gun built around that and forget trying to make something out of the 300RUM? What caliber is best for this range? Any comments or advise would be greatly appreciated. Again, I'm new to all of this so most of you have forgotten more about benchrest shooting than I know right now. Thanks for your time.