Breechloaded blackpowder gun

[Cannonfuse]

Hello! I’m making an breechloaded .50 gun which will be loaded with paper/cardboard cartridges, which in the rear will have a fuse like this:


At the moment the breech of the barrel, where the cartridges will be inserted, look like this:


So, I need to make some kind of locking mechanism for the breech that seals the cartridge in place. Do you got any suggestions on how this should be done?

I’ve seen quite a few different designs, originally I thought of making a cruel cannon of medieval-style like this:



But then i thoughts that it would be funnier to make a ”hand-cannon”/breechloaded pistol instead. And the old design above is clumsy and too awkward.

I thought of something like this:


This:



Or maybe this


There are also versions where the breechblock are screwed in place, but those takes to much time screwing and unscrewing, I want to be able to reload the gun fast.

Beside fast reloading the design has to be strong, fairly sealed and not too complicated to manufacture. Feel free to give me your thoughts.

[4V50 Gary]

Gas seal is the problem. I prefer a screw breech but you have to grease it (tallow & beeswax?) to ease the opening.