Some of the Civil War period military muzzle loaders had a powder chamber at the rear of the barrel. Your barrel may be fine. What type of patch jag are you using? If it isn't secure, the patches may come off when they get to the powder chamber. Try a bronze bristle bore brush in a caliber that allows the patch to get a decent fit in the bore. The patches will rarely ever come off a bristle bore brush. You can use a bristle brush as a worm also.
I'm accepting no questions regarding how I came into possesion of the information in the above pargraph, other than I used to own a Zoli Zouve many years ago.
If you are concerned about looking in the barrel find a gunsmith or shop that has a bore scope. It alows you to look at the barrel interior in very fine detail, and has a light. Only downside, you won't believe how rough with machine marks the bore of your favorite rifle is when looked at through a bore scope.