One of the niftiest guns I have seen at SHOT is the Excel Arms X-30R Rifle. It is chambered in .30 Carbine and accepts M1 Carbine magazines. A number of models will be available later this year, including a pistol version. The gun is blowback operated and has a heavy recoil string to slow down the bolt.
My only complaint is that the barrel of the rifle is 18″, not 16″.