I wish you a warm welcome at Subsim.com. Surprisingly
I have never succeeded to sink one of these Polish submarines, and surely never tried with the Deck Gun which performance has been highly reduced in WoS. If a damaged target sinks because of high waves or bad weather, then unfortunately you are not credited for the sinking. This may be one explanation, or it's a glitch in WoS.
Greetings and welcome!
