It looks as though the barrel key is passing through the barrel. It is quite high.
Germanic??? Yeah the lock does look like a Volkswagon, in profile.
I must admit that the work on the end of the barrel ( muzzle ) is not bad, and the quality of lettering ( although a lot ) on the barrel is impressive.
My knowledge of German is poor, but, did he write his whole family history?
You could strip the gun down ( throw away the barrel, lock, stock, ram rod, trigger, trigger guard, butt plate, tang, sights ) keep the screws and make a new gun.
Fred