It's a Belgian rifle/musket that I've had about a year (I probably posted the same question before). I don't think it can be relined without a breech plug.
It's a smoothbore now. I shot the other day for almost 3 hrs - great gun (.535 patched roundball, 60 grs of Goex FFFG. It doesn't like Pyrodex RS). Accuracy isn't great but not bad, either. I might just leave it alone and have fun with it.
I got this info from a Belgian rifle website:
"It is a military or rather, it WAS a military piece before a clever gunsmith merged it with a Dutch M1841 breech. It started as a M1853 rifled musket, was then converted by the Belgian Army into an 1853/67 ( an Albini breechloader). All the markings are Belgian military markings. The 59 on the lock indicates the original gun was made in 1859. My first reaction was to identify it as a M1853; but a close picture of the breech showed my first guess to be incorrect. The rifling has also been removed. M1853/67 guns are fairly common, but M1853s are rarities...because the conversion work was done so thoroughly, there are only a handful left.
I hope this makes it clearer...
André"
I wonder if the bulb at the bottom was formed when they welded a breech plug section to the barrel, and it wasn't a perfect size match.
What about a replacement barrel?