The same Museum keeps an other curious tool described as Wurzelstock-Schießgerät (a tool for blasting off tree stumps). The tool has an approx. 25 cm long barrel with a screw thread on on the open barrel side and a ring on the closed side with a touch hole. Dated to approx. 19th early 20th century. The tool will be filled with black powder and crewed in a tree stump and then lightened with a match. I guess you can imagine the rest....
A similar tool was presented here named as Stockbüchse (treestump gun) from Switzerland
http://www.ronmuehle.ch/seite.mv?10-20-00-00