I purchased a Tactical 512 a couple years ago. Out of the box it would double fire quite often. I took it back and they gave me another one. I shot it a few times and it ran OK. After about 100 rounds it started to not eject or fire some times. I should have sent it back or to CZ for repair but when I called them they didn't seem to be very interested. I took it apart myself and found that the bolt that holds the hand grip on was too long pushing up the return springs guide. This caused one of the guide rods to break. I bought another guide, shortened the bolt and it ran fine until I installed a supressor. Then it started to not feed often and sometimes the fire pin would not contact the shell. I removed the supressor and so far it ran 100 rounds without issue. Not sure why the barrel is threaded if it can't handle a supressor. I did email CZ but again, not interested enough to reply. Not a big CZ fan right now. I like the gun. Have a Thermo scope on it for night hunting.