Elias, does the end of the barrel, from the inside, look like a hexagon - six-sided? Your inside rifling looks like it has more than that.
I also noticed you have the pellet primer spring on top of the lock plate. Sharps changed from percussion to rim fire (?) and did not have the four pellet primer pieces on the lock plate. Could you pull the hammer all the way back, and with your thumb perpendicular to the lock plate top push backwards from the top round screw - big fat round head. The back end of that top piece (spring) has an "L" shape, and pushing back should expose few other parts under it.
If a converted '63 or later, Jobe or others correct me, but I thought these parts would have been removed.
One more biggie, do you see a spring in the front side vertical opening of the lock plate? If that's there, my guess is you have a mismatched rifle. Looking down at your lock plate after you pushed back the primer spring, do you see a piece that's right up to the top of the primer pellet chamber? I've read folks call it a nub or a piston. I'd love to buy it from you, if you'd be so kind. They're only found on fully assembled lock plates, and nobody has any originals or repros.