She needed a bit of cleaning up. All the metal work is brass except for the wheel rims, wheel washers, and axles, which are steel. At some point someone had polished the brass parts with metal polish (possibly brasso) so there was greenish white dried crud in all the crevices of the metal to wood areas. I got a fairly stiff tooth brush soaked with a little light Old English wood oil and got it all out. The barrel has been polished in the not too distant past since it also had polish residue around the trunnions, but I resisted the temptation to do anything to it--other than wipe it down with a rag barely moistened with some Scott's liquid gold.
The bore measures .710 and the only identifying marks I can find on the barrel is the capital letter "P" stamped on the right trunnion and "76" stamped on the left. Maybe it was made in conjunction with our Bi-centennial celebration back in 1976 since it appears to be styled like the cannon used during the American Revolution.
At first I guessed it was 1/4 scale but I'm leaning to 1/5 scale now. At 1/4 the 17 inch barrel would be only scale out to 5.6 ft long, but at 1/5 scale it would be 7 ft long. Many 12 pdrs of the period had 7 ft long barrels while 6 pdrs were closer to 5 or 5.5. However, in 1/4 scale the 11 inch wheels would only scale out to a diameter of 3.66 feet which seems too small based on the few drawings I've had a chance to look at.
I'm guessing that the wood is poplar since it has almost no grain. I am not a fan of blonde finished wood, but I'll live with it for now.

A couple of more shots--one with a 1/6 scale non-firing French Napoleonic Gribeauval 12 pdr. behind for comparison

Another two shots along with the 1/6 gun (it's barrel is a bit over scale also)

Cheers