Centermass,
The Field Manual for the Use of the Officers on Ordnance Duty, prepared by the Confederate States of America, Ordnance Bureau, published in 1862, is (understandably) very similar to The Ordnance Manual for the Use of the Officers of the United States Army. 3d ed. (1861), because all of these officers, teachers and writers belonged to the same family before the Civil War, and it's causes tore that family apart.
This would explain why the formulas given for "olive drab" paint are the same in each manual.
I think that it's safe to say that a concensus of historians agree that an olive drab color paint was used by both sides to cover their artillery carriages, limbers and caissons during the Civil War.