Great little examples of old school tech, but dandy little hand grenades when the wear gets to a point that the flash from firing finds a way around in to the powder chamber.
Not too surprising that they dead-ended, as far as the tech goes. Difficult to make accurately, difficult to keep working, and difficult to have repaired in austere conditions.
Lovely things, for the folks that could afford them at the time though.
There were a few other types of repeating flintlocks that used either a harmonica type magazine that was moved across the breech to repeat, or a revolving wheel type multiple cylinder. Pretty much all the efforts were dropped like hot rocks either due to difficulties or costs to produce, or a general lack of marketability when they were made.
Some had the standard BP issues of flame jumping from one charge to the next, others were physically fragile. Some seemed like a better idea than they were, such as the repeaters that used a stacked up series of alternating charges of powder and bullets, in one barrel with several flash ports along the side of the barrel.
About the time that machine tools were being made that made it economical to mass produce these, they were allowing the inventors of the day to create cartridge firearms, and thus they faded away...
Cheers
Trev