I've been finishing off unarmed (and sometimes armed---3 purple hearts and a fatality on my last patrol) ships with guns lately in RFB/RSRDC partially to test the complaints.
I guess I'm just not seeing the problem. I've fired at 4-5 ships, one a converted merchant gunboat (Aux Gunboat in RSRDC). I probably fired 150 rounds between all of them, with a fair % of those missing. All 4 sank, and 3 of the 4 were hit by only 1 fish, and were making way when I stopped them with gunfire. The 4th would have likely sunk anyway in time (hit by 2 fish, foundering), but I gave the gun crew soime practice
Last gun attack, as I came too far forward, and unseen 25mm gun was unmasked and swept my bridge (at like 300 yards) killing the OOD outright, and wounding 3 others.