[Krupp]

Originally Posted by Sailor Steve

Well, it's just that SH3 had several types of shells, and the best evidence is that while destroyers carried those types, u-boats were limited to HE only. I had always assumed that it was the same for US boats, but if Krupp's info is correct, then that isn't true.

Another detail:
"..., as the submarine is not equipped with gun power to equal that which may be expected on modern merchantmen. The submarine gun may be employed against vessels known to be unarmed or small vessels of minor resistant qualities. "

I was in a hurry with my post above, and forgot to add the source for that quote. That earlier, and this short one here are from a manual called "The fundamentals of Submarine Doctrine.Doctrine are derived from theWar Instructions, U.S.Navy; General Tactical Instructions, U.S. Navy; Current U.S. Fleet Doctrine and Tactical Orders" or something like that.