I'll pass on a screw build, they like to work themselves out over time. That rear trunion lets go and you will get a bolt to the face. I always hear people talking about how easy they are to take apart incase you have to replace something but for the life of me I cant figure out what you could break that would require the removal of either of the trunions.
The only thing screwed togeather on mine is the trigger guard. They were all loose and one was missing its nut. I thought about removing them and welding the trigger guard but they look so much like rivits I figured it would look cleaner if I just welded them from the inside.
On another forum somebody tried using u drives. The guy swore this way was just as strong as using rivits, I think he got about 3 months use out of it before the trunion let go while he was firing from the hip, the bolt carrier ripped his wrist open and he nearly bleed out at the range, had to be airlifted to a hospital. I welded the HELL out of the rear trunion on the inside, its NOT going anywhere lol.