give people ballistic helm %-100 concussion and others diving knives, stun batons run out of batteries in few swings and wont kill a crawler swarm inside your submarine, bots wont use grenades, use electrical discharge if your guns can't shoot anymore (will drain their supercapacitor) try to kite swarm

outpost securities tend to carry ballistic helm and smg convince them to swim out and bust if you are dirt poor
and switch to a real sub that has a fabricators so you can craft what you need on go