Thought I would post some pictures of some "Folders" that I have in my shop. The first three are side lever opening, the button on the left side will allow the barrel(s) to fold as it pushes the normal stop to the side. The Beretta has a cocking handle forward of the triggerguard that cocks and when pulled fully back allows the barrels to tip open and/or fold.
The skeleton stock on the 410 is kind of unteresting, I read in an old catalog that it reduces the weight 4 oz. The chamber length on the 20ga German folder is more than 3".

Regards and Merry Christmas to All you Gentleman