Your firearm started life as a Muster 1854 System Lorenz Dornstutzen. The Dornstutzens were used to arm the NCOs and third rank men - Schutzen - in Austrian Army Jäger battalions. The Dornstutzen rear sight is quite distinctive. It was converted to Muster 1854/67 Wanzl "trapdoor" breech loader by the Austrian Army in approximately 1867/8 as a temporary expedient following the Seven Weeks War with Prussia in 1866. Someone in Liege, Belgium, then converted the Wanzl back into a percussion muzzleloader after it was sold out of service by the Austrians, for sale in the African "gas pipe" trade. See the Liege ELG proof mark. You should be very cautious about shooting it. In the conversions, the Wanzl breach section was removed and a purpose made percussion beach section was added. Some were threaded and screwed into the barrel. Others were welded onto the barrel. The later conversions are potential bombs. Just because it passed Belgian proof 100 or more years ago doesn’t mean it’s safe. IF IT IS THE LATTER TYPE IT IS TOTALLY UNSAFE TO SHOOT. I've commented in several other posts regarding these conversions of Muster 1854, Type I and II, infantry rifle muskets; Muster 1854 Jägerstutzen; and Muster 1854 Extra Corps carbines; which you may find by using the search engine.
Regards,
Don Dixon