I tried to move one of the top guns a bit further from the other one and npc started to shoot with them, looks like a bug in the game.

Yeah that would be odd. The setup for the dual cannons is just 2 guns connected to the same power/trigger on the periscope. Not sure why # of guns would affect that. But let me know if you figure it out, and I will update the mods. Thanks !

I'm not 100% sure its a pathing issue. The bots will jump on the guns but not fire at anything. I have already previously tried remapping the pathing, but it does not seem to change anything with their behaviour, perhaps I'll try removing one of the guns and see if that works instead. :(

Sorry, I never play with bots, I'm always playing with 2-3 other people, so I never really created the bot pathing. It's easy to fix though if you go into the editor. I may update it at some point. Sorry for the trouble.

I second the question from Nyarlathotep, I just bought this sub and found out the hard way, NPCs don't fire the guns.

Is there a particular way to get NPC's to use the dual guns in this stage 4 sub ? They don't seem to shoot any anything that approaches the ship. The radial flyout orders menu for weapons offers a choice of 2 upper or 2 lower (4 in total). I have tried all 4 and it doesn't seem to change anything.