Based on the date of his admission to Ocmulgee his wounds most likely occurred on July 22nd as the regiment routed the federal forces from the breastworks along the Atlanta and Augusta RR cut in hand to hand fighting. It seems likely that his contusions would have resulted as men fought with gun butts, Bowie knives, fists, rocks, sticks, and what ever was handy.
As to whether he is the lost drummer, Jamie, I'd say "sure looks like it".
George, I agree that drummers in battle most likely carried snare drums, but the regimental band would have had a place for a bass drummer especially if they were to provide entertainment as well as to sound calls and mark cadence. I do know that the band has been a forgotten group in our research until recently, but Jamie and the rest of us are now on it. Again thanks for all you do.