This is the only McCoy I found in the units referenced:

W. C. McCoy, Private, Company D, 25th Regiment Louisiana Infantry, enlisted March 6, 1862 in Morehouse Parish, La. by Capt. Fluker for 3 years or the war, on sick leave at Ringgold, Ga. April 18, 1863 remaining so through June, deserted August 1, 1863 near Morton, Miss.

M320: Compiled Service Records of Confederate Soldiers Who Served in Organizations from the State of Louisiana