Percussion cap and ball. Very strange gun to have an accidental load in it.
It reminds me of the Great White Station Nite Club fire in 2003. Is the singer who lit the pyro to blame, along with the club owner and the fire marshall who passed the club for inspection? It didn’t have sprinklers, exits were obstructed, and the club had flammable material.
They are difficult enough to load when you intend on loading it and you know what you are doing.
Way too much missing information to even guess what really happened here.
They’ve been converted to cartridges. ,38 Special, maybe. Is that an 1851 Navy?
It looks too like a single-action; so he would have had to manually pull back the hammer??