I have the MKI version of this pistol. Out of the box, it has a couple glaring design problems (in addition to the erratic regulator):
1) A hard, difficult to adjust trigger, a well-known issue. After stoning the parts, the only thing that made it more predictable was generous use of lube, which needs periodic reapplication. There is little adjustment range, regardless.
2) A rotating barrel, completely unattached to the breech block. Without adding index marks for reassembly, this non-indexed barrel will take a different set -- and shoot to a different POI -- whenever the shroud becomes loose, either with vibration, or following a shroud cleaning. https://www.youtube.com/watch?v=YvwZClbLE_0
You will find yourself drilling and tapping set screw holes in the breech to fix the barrel permanently, but then it's resale value plummets.
3) It is well known that the cheap, Chinese o-rings are worthless, and will need replacement.