I think now is the time for someone '.....wot is cleverer than me at computin' should resurrect an article I did a little while ago about the ins and outs of setting up a correctly configured bolt.

Be advised chaps, that this is not FITTING a bolt or CHSing a bolt, but just the correct fitting up of a bolt assembly, according to the EMER bible and as taught to young Armourers......... and then practiced for many years afterwards

What A de E says about bolt head overturn is dead right. Although 10 degrees is the given acceptable figure, in reality, ANY overturn should be that the load of recoil is taken down the bolt body through the circular contact of the bolt head onto the bolt body and then directly to the locking shoulders and NOT the threads. An important point there