In the event that anyone is still reviewing this thread, I have a question: has anyone seen a Lanchester which has both the rotational locking screw at the muzzle end of the barrel AND the locking screw through the magazine housing. I have seen an example, which is labelled as a Mark 1 on the mag housing. I know that the mag screw replaced the screw at the muzzle end of the barrel, but are there guns which have both?