What kind of application? Just saying 1,000yrds isn't very helpful. If recoil and/or rifle weight and powder cost don't matter to you, then a big case magnums in 7mm, 300, or 338 that will throw a bullet with a BC over .6 and you'll be happy. 338Lap, 300win mag, 7mm rem mag or 7wsm.
For less cost and less recoil, over .5 BC 6mm and 6.5's. I don't have a 260, but have tinkered with one this year that's very pleasant shooting at long range. 6.5-284 has made me very happy, as has a straight 284win and 284 shehane.