Paper targets are better than wasting the life of a chipmunk. And will make you a better shooter faster.
You are probably talking about ground squirrels not chipmunks in Az. and shoot the hell out of them. They can destroy a field with thousands of holes. For them a .308 is the only choice you have out of what you gave. Not my choice as you can shoot hundreds of rounds a day. Will make you a great shot with your big game rifle though. It will be the best choice for varmints to. Not a great choice for anything you have to shoot. Others can tell you there choices of firearm, though you didn't mention other choices.
Last edited by limbkiller; 07-19-2013 at 11:35 PM.