If you are planning on skinning, fleshing, stretching, and selling , I would do a 17-204 or a 17-223. If your just out to kill coyotes the fast twist 22s and 6mm will work just fine. Unless you totally suck at calling, or you are barging into your sets, your shots should be in the 300 or less range 90% of the time. I have used a 22x47 for a derby gun the last 5 years. It does well at distance, but it also leaves large holes, and ruined hides at times. I think you will be happier with a point and shoot system out to 300 with minimal damage, than you would be with a heavier, larger bullet from the .22 and 6mm flavors.