now that's funny... albeit, if you handloaded , say some 105 or 110's, with say a 26 inch bbl, a 400 yd shot, after zeroing at 100yds, would come pretty fast, and easy. I would say with enough practice, 1000yd target shots could be taken.
a 600 yd shot on game, if you were really knowledgeable about your rifle, is doable. I am pretty fair with my remmy in 788 , and with my 6x24 mildot scope, I would take that shot.