I do not have any way of creating a picture for you folks right now but when one of my sons is over it will happen.
Confusion? Try this....
The barrels have a hook to lock into the breach the same as many other black powder guns. Near the muzzles is a brass slide to retain the barrels with the fore stock, the same as many other black powder rifles.
There are two hammers used to fire two percussion caps to then fire the gun the same as other black powder guns including my Pedersoli SxS .50 cal Kodiak rifle.. The barrels are clearly marked "B.P only" for black powder.
All of my other black powder rifles have breech plugs, not this one.
Any single barrel or SxS modern shotgun I have ever owned or shot used a barrel release lever to permit the barrel(s) to swivel then add or extract a modern cartridge. I cannot explain this any clearer but photos will follow in a couple of weeks.
I do not shoot pum0p action or semi auto rifles.
Thank you for your interest.
Ken.