I am thinking about having someone build me an AR for deer, coyote, wolf. It has to be cold weather durable. I don't have any of these caliber and I want it to be an AR. Distance, typically under 750, maybe plinking to 1000. I'd like the AR to balance fairly well and I'm thinking I don't want to go over 22" barrel if possible. Hopefully 8lbs., and under with scope. Off hand shooting and from a tree stand would be my typical set up, walking and stalking deer or my way in possible. What bullet weight and twist rate too. Any suggestions, experiences appreciated.