I misspoke earlier. The Joseph Lang guns built earlier than the one I currently possess were mostly all muzzleloaders. I have seen one that was within just a few serial numbers of this one that closely copied Casimir Lefaucheux's gun (the "French Crutch Gun", as it was derogatorily referred to in the English Gun publication of the 1850s, The Field) which was arguably the first successful breech loading shotgun design.