I got the rifle together today, I decided to shove the locking shoulder in without bothering to measure anything, probably a bad idea, but I didn't care. Well it worked, fired, ejected the first time. Second shot it locked up, taking considerable force to unlock the bolt and eject the spent cartridge, it continued to do this for the ten or so rounds we fired through it.
I think it's pretty obvious the problem is the locking shoulder, I just want to be sure that this is a symptom of the locking shoulder being too big or too small, and which one.
I'll measure it tomorrow and do it properly, I'd just like a little feedback beforehand, incase I overlooked something.
Also, anyone know where I can get all the gastube/gasblock parts for a South African gasblock? I couldn't get the original L1A1 gasblock to work (nothing lined up right) so I just put the South African one on there and haphazardly shoved some of the original parts on, the gas selector thing isn't held on by anything but the spring, so it comes loose regularly, and isn't very reliable, so I need the original parts.
Other than all those problems, the thing is coming together nicely. I got the Century receiver and the fit and finish was overall wonderful, all the parts fit in well, the barrel went in and fit perfectly, I managed to tighten it up with a wrench and used the original barrel shim to get it lined up vertically and tightened up nicely. There was one stupid problem I had though, they left a chunk of metal unmilled, which stopped the bolt from going all the way forward. My palm went straight to my face when I saw that, idiotic mistake. But otherwise it's a great receiver, feeds well, might need to polish the feed ramps slightly, but I really haven't had any problems with it.