A good place to start looking is:

Walker, James J. GA 50th Inf. Co.K

Other Walker's in this unit:

Walker, G.G. GA 50th Inf. Co.D
Walker, H. GA 50th Inf. Co.D
Walker, Isham GA 50th Inf. Co.A
Walker, J. GA 50th Inf. Co.D
Walker, Jasper GA 50th Inf. Co.A
Walker, Joel GA 50th Inf. Co.B Sgt.
Walker, John GA 50th Inf. Co.A
Walker, Love GA 50th Inf. Co.B
Walker, Richard H. GA 50th Inf. Co.C

Suggest getting his Service Record.

Also contact:
GA Dept of Archives and History
Civil War Records Section
330 Capital Ave SE
Atlanta, GA 30334

Gen Info: 404-656-2350