Danish to English Other Archaeology type of medieval lock

This was a kind of lock used in the 14th and 15th centuries. It would have had a key, because some keys were also found in the excavation... along with pots and kitchen utensils, but it was all washed away in a flood, so the actual quote from the text is not terribly helpful!

Det er rester af glaserede kander, sortgrå kuglepotter, sko og andre genstande af læder, dele af støbte bronzegryder, armbrøstbolte, nøgler til bultlåse og en enkelt bultlås foruden godt 20 hulpenninge.

Thanks for any suggestions!