I have checked many scources,and they did not have more than maybe 3x47mm qfr6pdr),guns in the colony,now they had about 15-19 37mmguns,from revolving cannons to qfr guns.Now Wissman had two47mm qfr guns.I have a picture in the german kamerun site here in the forum of the 37mm qfr,which you would probabvly have to use a mtn., gun model,The virtual armchair general makes a naval mount 47mm qfr gun (Houston guns),but you would have to put in on a gun carriage.you could also check w/chris dale owner of the German colonial uniform web site,he is very knowledgeable. I'll keep searching