I don’t know how it works in other ports, but in Singapore a ship carrying guns of any kind has to declare that in advance of arrival.
The guns will be carried ashore and stored in a safe storage and brought back to the ship on departure.
All expenses for this, incl. guards during transport, storage and paperwork to be charged to the ship-s local Agent and onwards to the ship’s account.
Failing to declare arms belonging to the ship may result in heavy fines. Any private guns found on board, or on a person ashore, MAY be subject to death penalty as per Singapore Law.