that brass piece could be a very beautiful cannon , 3/4" cal and 20" - 22" total length . 
then you got material for the trunnions also if its 2 feet long . 
if its 3 feet it could be a golfball mortar also , or maybe 2 . 
I attach an original drawing here from an artillery handbook dated 1706 
but this  is just my style of cannons , you probably want something from the cw period . 
the 2 at the bottom I really like . 
but its lots of work so I guess you need to put in a few bucks also , no one works for nothing , or almost nothing  

steel and other metal prices are the lowest now since approximately 10-15 years . 
they even talk about closing the steel plant here in town now . 
soon this can be a ghost town  . 
about the attacments , its very easy . 
when you finished your writing just click the "additional options" 
search for your picture in the computer and attach it
then just post it .