Now this is embarassing, the 70mm chamber is listed right on the "gun card".Was the gun card shown in the slide show in the begining? If you go back to the slide show now,it is shown; was it added later? There was an awful lot of discussion about whether it was marked 16/70 or not, and I never did see clear photos of the shotgun barrel's proof marks. Clear photos would have prevented a lot of misunderstanding.
Mike