To me it looks like a Belgium made box lock , caplock screw barrel pocket pistol . These were made in their tens of thousands for self defense in the days before gas street lightening . They came with a special octagonal ring wrench to remove the barrel . Inside is a chamber where the powder goes and the ball is seated on top of the powder then the barrel is screwed back on , this makes for much higher muzzle velocity . If you look at the pictures you can see the barrel flats do not match up perfectly with the action . Try to carefully take the barrel off with a suitable size smooth or padded jaw wrench , maybe use some penetrating oil first . Google Caplock pocket pistol . There were also flintlock versions with a pin that held the frizzen closed , and folding trigger versions in both actions , Most of these I have sold are in very good shootable condition because they were never used or seldom used . , some early ones came with folding bayonets .