GI Joe made a twin .40mm gun that was used on all kinds of US Navy ships from just before WWII until the Korean War.
This is a great toy, you get the gun, two ammunition magazines and one sailor. The sailor has no shirt and his helmet is white.
It makes a great mounting, line up a few of them for a small bit of a battleship or to staff a cargo ship.
It's nicely detailed and gives a good use for you GI Joe action sailor figures.
I managed to get three on sale, and have considered converting one to a 3 or 5 inch gun mount.