I was passing a Polish book store today to look for more books on edged weapons and suchlike when I reviewed one I saw before. This dealt with older weapopns presumably now in Polish museums or other hands as a result of the "asquisition" of private and public arms at the ending year of WWII.
There was a photo of an 1813 Parisian presumably double gun whose breech flipped up on a hinge just at the chamber. Obviously a breech loading muzzlkeloader. The thing which caused the breech to raise was a long top tang integral with the top or back breech which went back through the grip area and which folded into a nice loop to grab.
How this was locked requires reading in Polish if that information was given. The obvious (today) aspect of this design was that the flip up section looked exactly like the sliding breech of the Darne family of guns. My logical guess is that the later Darne design developers remembered that breech design and said, "Why not slide back instead of flip up?"
I suppose you could draw any number of mnechanisms including a central pivot pin which would permit the top/back breech to be raised by a lever going back as the top tang. It worked for "muzzle loaders" in that case and I'm wondering if there is any point in making something like that today.
