As many have already mentioned, a .243 would be hard to beat. If you want negligible fur damage then use a 55 gr. Blitz King (if you can find them) and drive them fast. I assume a Varmageddon bullet in similar weight would behave in similar fashion, and they seem to be more readily available. I purchased some since I couldn't find the Blitz Kings, and am just waiting to try them. The 55 BK out of my 6mm Remington Ruger American slings them at 3720 fps. Of the coyotes I have shot with that bullet, the norm on broadside shots is drop right there and no exits, and that's at 60-80 yards. Not sure how the bullet would perform at 300 yards. 70 gr. Blitz Kings could also be an option.
