Master Model produces finely crafted small detail parts for models which have been damaged or may be subject to rough handling. Their collection of antennas and pitot tubes are invaluable for the modeler whose friends (or former friends) handle models less than carefully. There’s a picture below, which appeared as a cartoon in an early IPMS Quarterly. This particular set is for the cannons of a Spitfire IXc.
The C wing had either one or two cannons in each wing, and possibly two more .303 machine guns outboard. The kit includes two sets of cannon and one set of stubs, so you can do either of the C wing cannon options, depending on how the aircraft you’re modeling was armed.