I like Uncle matt' s response.

For me, I' d be willing to take a shot with MY .30-06 at 600yrds, I' ve actually made a 400yrd shot, it never took another step. My take on it is that you use long range bullets for long range hunting, I used a 150gr Winchester Supreme Balistic Silvertip (up close-under 100yrds-this is best left to varminting, but it opens up nicely at low velocities produced from LONG ranges, btw, this was before I handloaded, but I' m tickled to death with the new CT bullets!!), and I knew where it struck for every 10yrds for 1200yrds, I put it exactly where I wanted it, and the deer dropped straight down. I' m sure that the cartridge is capable of killing game well beyond 1000yrds, probably could with the right bullet at 2000 even, but good luck getting it to hit anything out that far!! The real limitation of the .30-06 is its accuracy, not its power, it' ll do the job if you get it there, but when you get past 500-600yrds, getting there isn' t very easy. I get an average of 46" groups at 1200yrds with my flat stock Ruger M-77 .30-06, I' m still getting better than 1.5MOA at 600yrds (8-9" groups), I could hit a deer' s vitals with utmost confidence at 600, at 1000yrds, I couldn' t, plain and simple, I might get lucky, I' ve put shots through the X-ring at ranges from 800-1200yrds, but one lucky shot in a 40" 5-shot group doesn' t mean much when there is hair in the hairs.