RE: .243 or .308
I'd like to make a correction on the suggestion of cheep surplus ammo for the 308, they aint non!
I've never thought of the 243 as a varmint round, as arround here we have always used it on deer with great results .
Many shooters are using it on varmints however and with great results provided the right bullets are used.
I do hope you don't intent to shoot coons while they are in trees with any centerfire rifle as this is very dangerous, the bullet will come back to earth somewhere and could cause serious injury or death to an unseen person.
I have a 30cal 150 gr bullet which I removed from the exterior wall of my home after it passed thru the roof and framing of my carport, it was coming down at a steep angle from some idoit shooting into the air, a real wake up call!!