After this experience I don't think I'll be changing the gb again anytime soon. And now I know how to build an upper, which is a good thing for me, but probably a bad thing for my bank account in the long run :).
I've found some tips on here about assembling low pro gas blocks & I think I'll set the gb with blue loctite and take it to the range. If the bolt locks back and the outside of barrel is free of black streaks I'll reassemble the screws with red loctite.
There are several types of red loctite, so I'm assuming this was assembled with the common red loctite and I'm just a poor machinist/gunsmith - which is the most likely case. There are very permanant loctites meant for pins, etc that are basically indestructible. I ordered the complete upper from BCM with the old rail on it. ?

