This is my first cannon. My research tells me that it is best not to get into detailed discussion about the "original" colors of the pieces.
I did find some information in
Field Artillery Weapons of the Civil War by James C. Hazlett, which said the carriages were "OD green" and the metal was black. Somewhere, I even found the formula for the green color, but that sparked concern that the ingrediants used today are different colors than the ingrediants they used "back then". I found photos of some pieces at the Virginia Military Academy (I think that is where they were.) that showed red carriages. That was NOT going to happen!
My carriage is constructed of red oak. The axel is cherry. Cherry was the only species I had laying around the shop that was big enough without glueing one up. Due to the strength requirement, I did not want to do that. I am a woodworker. It was tough to paint, but it had to be done. It is a field piece not a decoration.
I also collect U.S. Military weapons and equipment. During my "travels in these circles", I found a paint formula for a "perfect match for a WW II foot locker". It was from Lowes and used an Olympic brand base. I don't know what it looks like, but have that formula, if it will be easier for you to get. Unfortunately, the formula did not match what my local True Value hardware store was able to do. However, he was able to call the home office and get a matching formula for their brand of paint. I was building some cabinets for my collection and purchased a gallon of paint. I had some left over.
This is a "brush paint".
The formula for True Value brand paint is:
Interior Semi-gloss
EZS-N Neutral Base
B-4y42
C-10y39
F-1
KX-13
That may not mean much to you, but it will to the paint store.
The black is just an aerosol paint (rattle can) from True Value. It is X-O Rust Professional spray enamel "Paint & Primer in One" - XOP18 - Satin Black - #125737.
All parts on the piece are either of these two colors. No primer - just paint. It has - maybe - three coats of the green at various times during the build. There is a brushable version of the black paint. I expect I have repainted the steel tires at least five times. They get messed up, when it gets moved across the gravel and I have to make it look pretty, again. Very simple process; block up that side of the piece, dip the brush in the paint, hold it against the tire, and spin the wheel. It takes about 60 seconds per wheel.
"Original color" - no, probably not, but it works for me - and I think it looks good.
Thanks for your comments!