A 16th or early 17th century rifle. In those days, German smiths were using rifled barrels, a Vernier-type or peep rear sight, and a version of a box in the stock. The wood was often dense oak, walnut or some other imported hardwood. The stocks were not sleek, and the bore sizes varied from those intended to be fired from the cheek rest, to those that had to be supported by the shoulder.
The lock deserves your best effort!