I see a Reuben T. Bullock who served as a Private in Company G, 41st Georgia Infantry. Perhaps this is whom you are seeking? He is the only confederate listed under the name Reuben Bullock. There are several Union soldiers listed under the name Reuben Bullock, however. The most likely candidate would be Reuben T. Bullock of Company C., 12th Tennessee Cavalry. He seems to fit your description.