Big Bro is right on, the farthest I have ever been able to range a deer with my lieca 1200 is 971 yds. if you wanna shoot beyond 700 you need to dial, the best setup is a kestrel or another type of weather/altitude monitor and a pda running a ballistic program.
Shoot a heavy for caliber high BC bullet at a moderate velocity and watch the fur fly!
The 6.5 gibbs is a 270 case btw, just necked down and improved to the max
RR