Picked up a 300 BLK upper from them, 12" or so, ran fine for the 150 rounds I had it for. Was on an Aero complete lower. Traded it away after the ammo jumped in price.
I owned at least 5 of these, the 4.5" barrel was more reliable than the 6 or the 3.5".
Own a few of the KelTec PMR's and would like to try out the new Rock Island 22 mag.