At the start of WWII, the U-boat packs operated with impunity in the North Atlantic and while their torpedoes sunk a lot of ships, their deck guns did a lot of damage also. This ended with the advent or air patrols and small carriers. Eduard has produced an excellent resin and photoetch kit of the 8.8cm gun used on the Type VII U-boats. My only recommendation is to check references in that on the later Type VII's, the gun was removed due to its ineffectiveness due to the threat of aircraft.
Eduard kit consists of 14 perfect resin parts and 15 photoetch parts on a single fret. The first dozen of these parts actually forms the gun sight alone. Fit is excellent but the parts are small with some being 2mm long and requiring bends. The rest of the gun assembly is smooth with the resin parts coming off the pour stubs easily and fitting perfectly. Add the adjustment wheels and tampion (gun plug) and its clamp and the gun can be set aside.