I' d go with a .223 remington. Preferably in an AR15. With the .223 you have the ability to fairly fast with a light bullet for moderate range shooting 0-300 yards and heavy bullets 60-75gr for shooting beyond 300. Ammo is super cheap and there are a lot of different factory loadings for it. With the AR you can have the best of both worlds, one light short upper with 16-18" barrel and low power scope for close range shooting and another 24" heavy barrel upper with fast twist 1-9/1-8/1-7 for shooting those heavy .224 cal bullets for long range work.