Let me team up 260rem. If you meant 1000 for big game, which I assume you didn't mean it like that, FORGET IT. Moving on. For a 1000yard gun a couple popular calibers are the 300s, 7mm Mags. There are alot less popular calibers out there. The tried and true 308/30-06 shouldn't be ruled out either. If you're wanting a whiz-bang howitzer-of-a-gun the 338 Lapua and several of the big Weatherbys are good options.