My characters are in a sea battle (on a minor scale - longboats vs. fishing boats) and from one of the boats a shot is fired by a "huckbuk" (there are various spellings).

This is (more or less) a prototype of a rifle, though it has no stock. The 'huck' is a hook which is used to support the weapon and reduce recoil. I have to describe this without becoming a teacher. Probably one character will explain this to another, though that is difficult to do in the heat of battle.

Happily, this character has heard of this weapon from his current employers, who actually saw such a thing during their trip to China, thirty years before Marco Polo decided to visit. But then, I have to explain that, too. Alas, the poor author.