John,
Based on the brief account by Lt. William F. Pendleton, Sgt. Wm. R. Hersey, Co B, 50th Georgia Inf Regt, was killed near Rose Farm, likely from the terrible Federal artillery fire coming from the area near the Peach Orchard. Many 50th Georgians were killed and wounded in this area during the initial assault by Semmes' Brigade on July 2. General Semmes and Lt. Colonel Kearse, 50th Ga commander, were among the casualties. Pendleton did recount his war experiences to his children, and daughter Constance Pendleton had them published in a family history, entitled "Confederate Memoirs: Early Life and Family History, William Frederick Pendleton [and] Mary Lawson Pendleton". I did extensive research on the role and location of the 50th Georgia at Gettysburg, devoting a chapter to the battle in my history of the 50th Georgia, entitled: "Wiregrass to Appomattox: The Untold Story of the 50th Georgia Infantry Regiment, CSA".
Pendleton did not specifically pinpoint where Sgt. Hersey died, but I believe his account places Sgt. Hersey near Rose Farm. The Pendleton account is as follows: "We were going toward a peach orchard, but were ordered to right oblique. The firing was very heavy and dangerous. Colonel Kearse and Sergeant Hersey were killed. I didn't know it at the time, but both were killed dead." Pendleton helped bury Colonel Kearse's body on the Rose Farm property the next day. I would assume Sgt. Hersey's body would have been in the same general area, although I found no specific account of the location of his remains. It is possible that his body was unrecognized as the result of his wounds. The bodies of Colonel Kearse and several other 50th Georgians were removed from Gettysburg in 1871, and reburied in Savannah's Laurel Grove Cemetery. Those who were recognized were given headstones. The unknown soldiers were placed in a mass grave. Sgt. Hersey's remains are likely in a mass grave in Laurel Grove, although it is possible that he could have been placed in a mass grave in Richmond's Hollywood Cemetery. Unfortunately, we will probably never know the exact location.
Hope this helps.