I'm betting the twist in the barrel will be wrong for pistol bullets, the rifling depth may be wrong as well...Can you look at it and get a name off the gun, caliber would be nice as well...

If it were me, I'd drop the powder charge down to 65-70grs with the patched ball and see how she grouped at 40 yards...If it groups well, and I bet she will, I'd take it hunting...