This is one of the cannons I used in the Deutschland's stern turret. Inspired by the BIC, with very similar assembly and printing requirements. Just the dimensions are different.
NOTE 1) due to modeling issues with the 1/8NPT threads on the bottom, you must print this file 2.5% larger than normal. Otherwise you won't be able to screw in the air fitting.
NOTE 2) due to the reduced slope of the ammunition tube, this cannon sometimes has feed issues. I have not yet solved these, if anyone has feedback please let me know.