Also depends on ammo. 175 Match (Fed) stays supersonic slightly past 1k, depending on the rifle.
I built mine in .308 off of a Mauser action (Vz24), and am quite satisfied. It all depends on how much effort you are willing to put into the rifle. Little things matter, and can cost money. My trigger was almost $200. I spent almost a week lapping in the bolt, and another couple days polishing the ways. I used a pull-through reamer for chambering (about $150 for the reamer) and a LOT of elbow grease throughout. I did get a deal on my stock....one of the varmint laminates from Midway that I finished myself, then used Marine-Tex to bed it top and bottom.
This is just to give a start on the work I did. A buddy of mine did a LOT of machine work on this thing, and it took about 4 months to get it together RIGHT.
If you want a good out-of-box gun, go with Iron Brigade Armory or Texas Brigade Armory. They're about the best guys I know for extreme-range weapons.
Plan on buying a VERY expensive piece of glass. I use a Nightforce NXS, and recommend them highly. In my humble opinion, the best glass for the money. Get good rings. Badger Ordinance rings are some of the toughest I've seen. They are also fairly expensive (around $100).
Best of luck!