Got a lot done at the COBP II today.
Initial fitting of the receiver parts:
First I pinned the front trunnion in place temporarrily with a rivet to find the best placement for the rear trunnion to fit the top cover. The rear UF trunnion was first trimmed down to remove some unneeded weight. I also had to trim the top bends on the Tapco flat to allow the sides of the receiver to sit flush against the trunnion. I then notched the top cover to clear the front trunnion and the receiver bulges. Once everything was fitted properly, I clamped the rear trunnion in place and Scooch welded it in place through the rivet holes for me. I ground the welds down flush with the sides of the rcvr with a grinding wheel to get them close and then finished it with a belt sander.
Since this is a pistol and isn't using the UF rcvr holes, I ground a few washers to fit the large UF pivot holes and tapped then into place. Scooch did the welding honors again and plugged the rest of the unused rcvr holes.
I noticed that the bolt carrier didn't want to move more than about an inch forward when installed in the rcvr. After looking it over, it seems the little top cover notch/ GB retainer I had welded to the top of the trunnion was sitting a little to low and was binding the BC. To fix it, I used a dremel to thin out the top inside edge of the top cover retainer. I also used the belt sander to thin down the top edge of the bolt carrier. Between both of the fixes I was able to get about 1/16" clearance between the two parts without having to mess with the rail groove in the BC or the rcvr top rails.
Next thing was to fix the top cover fit. I had to trim the bottom edges since the top cover sits at a little bit of a rake. A little time on the grinder and everything was lined up. The top cover kinda has a raked hot rod look to it now. Cool side effect of the custom fron trunnion screw up I guess.
Checking safety lever clearance to top cover:
Since the top cover has that forward rake to it now, I had to adjust the angle that the safety lever stops against. A few seconds on the grinder and it fit perfect.