This is a short gun with a Crown cast in relief on the 1st reinforce. The crown is eroded and difficult to decipher clearly. It is believed to be a continental piece that could have been cast at almost any time between the late 17th and late 18th Century, it is 53 inches long and 3pdr in calibre.
An educated guess would be that it was produced for one of the minor principalities of Europe, possible one of those making up, what was, the Holy roman Empire.
This gun is on loan from the Royal Engineers musuem and was obtained in 2010.
Any guesses?