Longshot, this question gets asked all the time and the choice is yours to make. It all depends on what criteria you are looking for to kill game with.
Do you want a rifle/cartridge/bullet that will penetrate, expand and exit or do you want to put a pencil hole in the side of a deer? You can easily do the math with an online balistics calc.
External Ballistics Calculator
IMO, for a "hunting" cartridge to "effectively kill" deer size game with @ 1000 yds, you should be shooting a minumum of a 7mm STW with a good MV and high BC bullet to get you to 1000 yds with enough velocity for expansion and energy/momentum for penetration. With most bullets, a 7mm RM, WSM, 300 WM, WSM, 338 WM will not get you there.
Hope this helps,