"That's all true but through the entire war the most commonly used artillery piece was the Napoleon smoothbore."
According to this website: http://www.civilwarhome.com/artillery.htm
, during the Civil War only about 1,200 bronze 1857 Napoleons were produced for Union service, and half that for the Confederates
Parrot rifle production was approximately 600, and US Ordnance rifles about 1,000, giving the rifled guns rough parity with the smoothbores.
Of course, earlier models of bronze guns were in use during parts of the war; how many I've not been able to determine.
What strikes me, though, is that if those numbers are correct, it seems like such a very small number of field guns for armies the size that were in play during the Civil War.