300 Blackout 16 inches threaded for that Sound Suppressor down the road. Can shoot supersonic 125 or 150 grain ballistic tips and kill deer easily at 150 yards. Zero recoil! Or shoot big old heavies 225 grain hollow point outlaw state bullets at 1050 fps through the suppressor for Hollywood Quiet. I have been shooting the 300 blackout's predecesor 300 whisper for 12 years and 30-40 deer later with zero crips or run offs feel comfortable saying the round is a good whitetail choice.