Warning: read the individual description of guns to check if it is compatible with your planned prow. All guns can be fitted to prows but some may require filing/trimming for a snug fit.
Warning #2: The Engineering Corps Battleship is an M3 class ship = Medium prow gun. The mech prow tapers towards the bottom so I recommend the Armbruster cannon
‘Dreadfausts’ can be purchased separately and attached to the end of barrels for increased single-shot penetrating power.
Large = M1, M2 class ships, ~30mm length
Medium = M3, M4 class ships, ~24mm length
Small = M5 class ships, ~19mm length