There was a problem with piracy in the Carribbian in the sixties. Not highjacking but stop and rob mostly for V&A items like electronics, personal items and perfumes. This led to a lot of it being transported by air which gave a second lease of life to Constellations and DC6s converted to freighters.
In the harbour at Belize I saw a tramp freighter being unloaded. On its foredeck was what looked like a Bofors anti aircraft gun on a plinth with its barrel parked below the horizontal.
I do not think they had any trouble.