Powerline 1000: How to align barrel pivot and install screw?

I am cleaning up a Turkish Powerline 1000 (Hatsan 60?). I removed the barrel to press on a muzzle device, now I want to re-assemble. Of course, in it's closed position - or any other - it is under spring pressure from the locking lugs so the hole in receiver and barrel block do not align. I can't find a position that lets me close that last tiny bit of alignment to insert the screw. How do you pros do it?

Followup - were to buy new breech seals?

Finally, is there a guide to disassembling the powerplant on this gun?