I might stand corrected. The Augustus D. Coleman in Company F, 33rd Arkansas Infantry, could possibly be your man, with the “D” being a mistake made by a NARA copyist. This unit also originated in Ouachita County, and Augustus D. was age 25 on 03 Jul 1862, which fits the age of A.O. Coleman from the census. I did not find another Augustus, A.O., A.D. etc, Coleman in the 1860 Ouachita County Census. There are others who can probably clarify this.