Hello all. New guy here been stalkin for a while tryin to learn new things ( comes plenty hard for me ). I have a passion for hunting coyotes ( I'm new at that too ). I prefer to call em in and the closer the better. I absolutely love to paste em with "Sledge" but there are times when hunting with some of my buddies and also when scouting that I get a chance for a shot out around 600-700 yds. My longest attempt/kill to date is 523 yds with my AR10 .243. I have recently gotten rid of this rifle and want to go back to a bolt gun. I would like some suggestions on what to chamber it in for busting these dogs at extended (for me) ranges. I like 6mm's for the quality of bullets but would also like something with a little more thump. I'm also concerned about the 6mm bullets' "on game performance" at these ranges. I'm wanting this rifle to be "purpose built" so longer tubes may be considered. Thanks for any help. Steve.