1000 yards? Sure it can be done but buy only probably less than 1% of the hunters out there. There are so many variables that come into play and conditions must be perfect. Heck a 10 mph crosswind will drift a bullet 3-4 FEET at 500 yards. Now take into account if the animal moves even a little.
A person really must be accomplished in this discipline to even comtemplating 1000yd. shots at any big game.