I've owned a few of them, and both had the same (potentially dangerous) issue
The "shelf" for lack of a better term, in the bottom of the newly manufactured frame, that the bottom of the lock frame bears against, was milled too low ....allowing both guns to unlock prematurely. This resulted in catastrophic results with a Navy Arms "TU-711" .....shattering the bolt stop,cracking the upper/bbl extension, and dumping 3 rounds f/a before leaving the bolt on the floor next to me.
A BTC imported gun ("Type 43") had the same issue.... but not as severe.
Both also had issues with poorly fitted sears.... the internals are a hodgepodge of C96, M-712, and Chinese made parts of questionable metalurgy
I sold them both as parts guns .....and IMHO, they are more "display" items than safe, reliable shooters.