There is some serious misinformation in this thread. Short answer to can a 308 be used at 400 yards, yes. Long answer, it depends on a lot of factors (like others have said). While the 308 can punch paper at 1000 yards, and do it well, that's not the question. We are talking about ethically killing an animal at 400 yards. Assuming skill of the hunter and necessary accuracy and understanding of the bullet's flight path, the issue becomes the bullet, impact velocity, and game animal involved. I shoot Barnes TTSX in my 308. Based on Barnes' old documentation and hunting experience (mine and others), impact velocity should be around 2000fps for good bullet expansion, and no lower than 1800fps. 2000fps is right at 400 yards, and 1800 right at 500 yards. Personally with elk, I want at least 2000fps at impact for good expansion and penetration, so with a 308, my limit is 400 yards. Deer sized game, I'd be comfortable to 500 yards. If the bullet is lighter and faster, chances are it will expand better but at the sacrifice of penetration - not good for large game animals. Lighter, shorter bullets typically have lower BC's so wind and trajectory offsets are larger. A chronograph and shooting app. is paramount to becoming a long range shooter. Neither is a substitute for marksmanship, but both are necessary to become a good marksman at long distance.
