RE: AK-47 ???
If you are just plinking almost anything will do... Having said that if you really want a gun that will blow your socks off look at some of the AR variants that are set up for varminting... Bull Barrels, floated, low mounted optics rails, etc.
My Rock River Arms Varminter will shoot better than any other gun I own... 1/2 inch groups at 100 yards easy!!! I have 3 sakos, 2 kimbers, a few rem 700, a browning a-bolt, etc. None will even come close... One hellava fun gun to shoot. Also .223 ammo is super cheap and can be found anywhere... My gun will shoot withe 1/2 inch accuracy with the cheap blue box Black Hills ammo!!! No reloading necessary!