Haha. I love that I'm not the only one nit picking the details.
And I was still trying to figure out just how said questionable revolver ended the story the way it did. 1) In regards to plot, if the gun is broken, why is it being kept around? What was it? Someone's heirloom? [Wonder if the novel explained it better?] 2) If its a broken trigger, I wouldn't expect THAT sort of result from a revolver. A bent barrel might, but not a broken trigger. But now that you bring up what it SHOULD have been [likely what the author intended], it makes more sense. A flintlock or percussion cap has a loose powder pack right down by the trigger, unlike a bullet with the powder contained in a casing. That makes the fatal misfire from a broken trigger seem more plausible. So the artist's lack of research was unfortunate in that it affected both the aesthetics and logic of the story for those who know better.
This is the second historical manga I've seen the wrong type of firearm in. This is supposedly Regency England, just after the Battle of Waterloo (1815). The gun depicted is a revolver, which didn't come into use until the late 19th century. In the time this is supposed to take place, the weapon would have been a single shot flintlock or percussion cap pistol. One might as well show up at the Battle of Bunker Hill with an M16.