Before and during WW1 the designation of naval guns was L/xx (L stands for lenght and xx was the barrel lenght).
For example: 8.8cm/45 SK L/45 (the predecessor of the WWII U-boat gun)

After WW1 until outbreak of WW2 the designation was C/xx (C stands for construction, xx was the year of design)
For example: 8.8cm/45 SK C/35 (used on type VII U-boats)

During WW2 the guns had the designation Mxx (M stands for modell, xx was the year of design)
For example: 3.7cm/57 M43 (late war AA weapon on U-boats)


So the designation c/95 means that the gun was constructed in 1995 (1895?).
Where did you find c/95?

Regards
Rainer