When you start to stretch it beyond 400yds you really need to understand the science of long range shooting. And anything from 800yds to 1000yds and beyond you REALLY need to understand. You need to find a load that is consistant in velocity to begin with. You want to choose a bullet with a high B.C. Your going to want a heavier bullet, when you look at ballistics and energy at long range you will see why. You need to research ballistic programs and understand how to work, what they do, and how to use one. There are so many factors that effect your bullet when you get to longer ranges. Reading wind down range alone is a skill in itself. If your gun turns out to be capable of the longer shots then down the road you may want to look at NightForce optics. In my opinion they are the best. Good luck with your new project, that caliber when set up right can be a great long range weapon.