I'm surprised no one has suggested this yet. Its kind off early to know how they are going to shoot accuracy wise but you might want to wait and see. Seems like it might just be what you are looking for.
300 aac blackout
http://ruger.com/products/mini14TacticalRifle/images/5864.jpg
300 aac blackout
http://ruger.com/products/mini14TacticalRifle/images/5864.jpg