chuck - if you go to the amunition mfgr web site, they have ballistics charts for all the ammo. Includes speed at various distances, ft. lbs of power, and bullet drop. You have to look at the chart for the specific shell you're firing.

I don't shoot a .270, but my WAG is that there will quite a large drop at 400 yds compared to 50.

Also, it sounds like it might be difficult, but if you think you're going to shoot at 400 yds, I really think you need to practice hunting position shots at that distance. Myself? I wouldn't even consider anything beyond 200 unless I practiced a lot at longer distancesand also I'd need pretty decent field conditions (good position, good target, good rest) before I'd try it. But I'm super conservative, sometimes more than necessaryprobably. Good luck.