The additional information as to his family's home helped narrow down units to look for him in. He did not die in camp at age 19. Calhoun Scott has a remarkable record - you really should order his CMSR from this site: (helps support these message boards)

http://history-sites.com/research/

Calhoun Scott enlisted as a private at Woodville on 24 May 1861, in Company D, 1st Battalion Mississippi Volunteers. This company subsequently became Company D, 21st Mississippi Volunteers, and served under that designation throughout the war.
He is present, on all muster rolls that survive, until his death. On the Jul-Aug 1863 muster roll he is listed at 3rd Corporal. Since the muster roll preceding that one is missing, we cannot determine the exact date of this promotion.
The Jan-Feb 1864 muster roll indicates a promotion from 4th Sergeant to 3rd Sergeant on 1 Feb 1864.
The May-Jun 1864 muster roll states: "Was killed in front of Petersburg Va June 23, 1864 by enemy's Sharpshooters."
There is more information including a full listing of all battles the 21st was in, and whether he was present, missing, on furlough, etc. for each one. A remarkably (almost) complete record.

Follow this link to a history of the 21st:

http://www.mississippiscv.org/MS_Units/21st_MS_INF.htm