7 prc, 300 prc, 300 win mag would be my top 3 in no particular order. 28, 30 Nosler, 7 rem mag, 300 and 338 RUM would be other possibilities for long range hunting including elk. My current long range gun is a 300 prc which replaced a 7 Rem Mag.
FWIW; 1000 yds on game is a long, long, long...