I am not awae if he produced any rifles my the method, but Henri Pieper definitely produced double shotguns in wihich the tubes were threaded into a steel one piece breech piece. These were "True Monoblock" breeches though Pieper did not call them that. I am not certain but highly suspect the Beretta firm coined the term Monoblock & perhaps even copyrighted it. The tubes on this Pieper system (Of which I have one) only go about half way through the breech piece & at least some of them were marked "Modified Diana" (As is mine). They are pictured & described in a 1911 "Alfa" catalog, but preceded that date by some years I believe.
