It has been a couple of days (or 20 years ) since I have used German , but the opening seems to be comparing his german made cannon to one made in Montreal, Canada.
Kind of an apples to oranges thing though 'cause one is cast iron (and lined) and his appears to be steel.
Of interest also is that one of the ways to disable the early guns was to dismount it and break off a trunnion on cast barrels.