Don't! A lot of stuff was made in Japan and shipped over here. Most were sold as wall-hangers. They were never intended to be fired. Unless a competent, BLACK POWDER Gunsmith checks the gun out and pronounces it fit to be shot, I would leave it alone.
50 years ago or so, my father bought a pistol that was a replica of the Tower Pistol. It was .62 smoothbore. The frizzen was soft, so Dad sent it off to Dixie Gun Works, to have the frizzen Case-hardened, and he also bought a scissors mold in .62 caliber to cast RBs. When the frizzen came back, he bought a pound of FFFg powder, and we first test fired the gun in the back yard shooting blanks. Just to deal with getting the flint set correctly, and getting sparks. In 1962, we took a long trip down to Friendship, where my brother joined the NMLRA, and went down to the pistol line to sign up for a practice target, and shoot that huge pistol. Using two hands, he was able to keep shots on the 2 foot square target frame. There was no rear sight, and he had no idea how much powder to use. So, he tried 40 grains, and the ball hit the vertical post that held the frame up. No windage problems with that shot. Half the ball was visible in the wood frame that was struck, and we dug the bullet out for keeping. I believe he settled on 60 grains of FFFg powder and put a hand sized group on the target before he finished. He was happy. We were happy. Some of the guys shooting on the range, but NOT Shooting at that relay because it was too hot, smiled and laughed at how accurate the gun could shoot- way beyond their expectations. Several came down to look at it.
Now, understand. Dad check the bore of the that gun thoroughly before he bought it. The next shipment the store received had barrels with open seams under the stock at the rear of the barrel- definitely wall-hangers! We spotted this, alerted the clerks, and all those guns were re-tagged- FOR DISPLAY ONLY. DO NOT FIRE. The boss was angry when he was shown what he had received, as he was expecting to receive pistols similar to the one we bought earlier, that could be shot, if they had a little work done to them.
Oh, we paid less than $30.00 for the pistol. Dad sold it years later to someone wanting it to fire blanks at New Years, and on the 4th of July. He didn't even want the ball mold. The Trigger pull on our gun was the other thing that had the need for work- it was next to impossible to pull the trigger!
