Okay guys, I ran out and took a better look, results as follows.
Not cast iron, steel.
Diameter outside, end of barrel is 4.5", inside is 2-3/8". Net wall thickness a hair over one inch.
Length of 52.5" outside, inside barrel is 48".
Trunion diameter of 3", length of 3.5".
Base of cannon to center of trunion is 20".
Diameter of exterior cannon at base is 4-1/4".
I'd guess it weighs in at around 120 lbs.
I took a few pictures, I'll upload tomorrow as I download from camera.
Could find no maker marks on it, will be calling the owner tomorrow for more details.
Thanks for the listen and all your help.