Fiendish Fabrications have released a set of 28mm Harpoon Guns.
From their announcement:
The first item in our new range of “stuff we don’t have a name for yet” is a set of two 28mm Harpoon Guns. They are cast in two pieces and are suitable for anything from pirates or naval or aeronef vessel.
We have several new products coming soon leaning more towards the scenery and accessories category tending toward the VSF genera. So get yourself ready with some new pots of brass paint and hopefully we’ll be able to provide you with enough rivets to warm the cockles of your heart.