Thanks Spiri. You must be familiar with the Museum of Artillery and Engineer Troops nearby. I love old artillery but was unaware of that great museum until I found the X???? website with many photos about 8 years ago.
If you have photos that are different from those on the website, particularly any of the more elaborate items, I know they would be welcomed on this site.
I missed a wonderful model that once belonged to Potemkin, had his coat of arms cast into the barrel and repeated in paint on each side of the carriage, at auction. I was "underbidder" sadly. It was antique, original, and in great condition. As I recall it was about 50 cm long, total.
Here are some larger ones identical to the smaller one I was trying to get.
http://www.stephenwoodresearch.com/port/pot01.htm