Forgot to say - I unloaded this gun when I was 15. Had, as I recall, some tissue wadding & a hunk of metal like a washer loaded in it. Back then I was Immortal so I loaded this old forged-iron-barreled musket with shot & annoyed sparrows, &c with it.
My Potsdam musket is dated 1833 on the top left flat of the barrel, near the breech. It was converted to percussion by the Germans. I do not know if Northern (Pennsylvania, in my case) forces actually used these early in the war, or if the North simply bought them to keep them away from the Confederacy. It does have a rear sight. I guess the Germans, who after all did invent the rifle, felt that even a smoothbored gun should be aimed. Many of these muskets were cut down for shotguns after the war.