something about that gap between the pistol grip and the back of the lower receiver.
so, at the factory, G uses a jig to index the buffer tube, torques the assembly, and done.
receiver end-plate doesn't index the buffer tube.
if you disassemble it, if you don't have a jig, it's just the good old Mk 2 eyeball to get it all straight.
i guess you ought to be using a jig for alignment anyways, especially if you own the Bentley, not just your two knees for this creme de la creme of rifles, eh?