Lancaster,
what a wonderful piece of history you have there - a true gem!
I'm with fuhrmann in this case, I would only feed this baby with BP.
I sincerely hope the crack Tinker found (I missed it first time) won't affect the safety of this old gun & be repairable without damage to that beautiful engraving!
Fingers cross for you mate!
Would love to see a video of the whole loading, firing & unloading process of this type of rifle/gun.
Lovely engineering & artistry rolled into one neat package!
Love this stuff
Cheers
93x64mm