Deer at 1000yds , all thats needed is a 260 Remington , I killed just short of 1K this year no problems. In a mauser action I'd go with a 6.5-06 to get an extra 200fps out of it.
Now 1500yds is a whole nother story that added 500yds is a LOOOONG way past 1000yd , I'd say a 180gr Berger launched at say 3000fps , maybe froma 7mmRUM or close , a 240gr Sierra Match King launched at 2900-3100 fps , for a 300RUM minimum more like a 30-338 Lapua imp of 300AX , or maybe the biger 338's ike the Edge or 338 Lapua imp or 338-378Wby , andhting to get a realy high BC bullet .680+ out close to 2800+fps so do on a deer at 1500yds