Have another HK-51 for sale, built exactly the same as the last one. It is built by RGS on an FMP (Portugal) reciever. These are made on actual HK tooling and have been banned from import since the late 90's. It has the flapper mag release installed and utilizes the latest truncated cocking tube. The barrel is cut down to 8.31 inches and threaded to HK specs. A fake suppressor is fitted on the gun to bring it up to legal length. This is easily removable if you decide to register it as an SBR. The gun has been assembled using HK, FMP and the required number of US parts. Feel free to email me for pics or with any question.