Will be brief on this as I'm getting ready to go south. Surface guns on Merchant ships were the
big guns mounted on the bow and aft. Most had a
3 inch 50 on the bow. It was an excellant aircraft gun and also a surface gun.( Surface gun means elevation is limited) The best and most desirable gun for the aft was the 5 inch 38. This also was a good gun for aircraft
and the best surface gun we ever had. All newer
ships had them. Some ships had 5 inch 51s and this was mostly a surface gun and very slow on loading and getting ready to fire. And some had 4 inch 50s and this was a surface gun only and slow loading. The slow loading mentioned for both of these guns was due to the many steps that had to be done. Mike your dad was right on about these last two guns.