A Goggle search, Orr's Rifles, will give you an awful lot of information.
Here also are two of their webpages:
http://www.geocities.com/Yosemite/6648/Orr_Rifles_Main.html
http://www.researchonline.net/sccw/unit98.htm
Obtaining copies of his Compiled Service Records will give you pertinent information on his service. Additionally, he may have filed for a SC Confederate pension as well perhaps as his widow. See the advertisement above for this service.
George Martin
Charles S. Davis
Residence was not listed;
Enlisted as a Private (date unknown).
"L" Co. SC 1st Orr's Rifles Infantry