fast update:
Fired today...
The brazing on the rear mount didn't hold... and the flash hider and bull barrel set screws came loose. Not dangerously but loose.
So gotta fix the stupid mount... thinking about drilling and epoxy this one. IF the other breaks loose will do the same.
Also, it will only fire a single round. As far as I can tell the bolt doesn't blow back to chamber the next round... so I have to manual cock, eject, load each round. bummer. No idea if it's because of the weight of the parts, or weak loads.
After I fix the mount I will try again with parts off to see.
Range guys freaked out over it though. ^_^ Looks cool on video with big flames