Well, for reliable sniping at 1000 yards you will want something ballistically superior to the 7.62x51 NATO (.308 Winchester) round/M110 package.
The .308 Win. bullet transitions from supersonic to subsonic around 625-700 yards, causing the bullet to become unstable and seriously degrading accuracy to unacceptable levels for a sniper/target shooter.
That's what the cartridge/rifle packages in the 7mm-8mm magnums (which includes the venerable .300 Winchester and Weatherby Magnums) are best suited for, which cover 1000 yards quite nicely. :-)
Over 1500-1600 yards is the realm of the BMG .50 caliber/rifle packages.
Stop pretending you know what you are talking about...
Try telling Palma shooters that .308 isn't reliable to 1000, they will get a good chuckle out of that. Further, my pet load, 175gr Sierra Match King + 44.5 grains of Varget is quite safely above transonic at 1k, thank you very much.
Magnums have their place, I love my .300 RUM -- but a vast majority of the time I shoot my .308 --- half as much powder, cheaper bullets, cheaper brass, and I don't have to replace the barrel after 1000 rounds. Plus, if you can hack it at 1000 with the .308, with a Magnum it is easy mode (if you can ever call 1000 easy).
And FYI, there are better rounds than the .50BMG for ELR precision shooting, assuming you aren't worried about damaging vehicles, buildings, armor, etc.
