You know what, Terry, I think you are correct. I was talking to a friend in Texas about IKE and not paying enough attention to this gun. It sure does look like an 1845 to me now, and probably a 24 Pdr. also. The muzzle swell really looks the same as the 1845 and the taper starts in the correct place too. The only 18 Pdr. we have ever found is at West Point.
Terry, Yours in Waycross looks like a perfect match to the Padre Island gun. I think you nailed it, a 24 Pdr. Model 1845 Iron Siege Gun, a fine looking siege and seacoast type cannon.
T&M