I'm not sure how he was shot. Back of the head would indicate a retreat to me, but I wasn't there. Who knows?
I will say that the pressure from a ACW weapon and newer weapons is a whole different thing. While the rounds were the same with pistols (with post war replacement parts) the range wasn't exactly huge. The rifles being used were about 900- 1,000 yards out. Give or take a soldiers aim and ladder sights.
Story is that Bill and another man, perhaps J.S. Raines son charged through a portion of of the MSM ambuscade and were shot from behind. That element was a Mounted Infantry portion of Cox's Command who were armed with sidearms as well as P53'S . Anderson fell from his horse dead, Raines died in the wounds , his body found later.
He was the son of Confederate General James S. Rains. His first name may have been John, not sure at all. Some accounts lists him as having escaped, and others say he was killed. No clear record on him exists. He, his bothers and sister are listed as Capt. John E., Edward H., Samuel H. and Ellen T. I can find nothing more about him for now.
I was in Orrick, Richmond and Lexington yesterday, but did not go back to the graves of either of these infamous guerrillas. I am confident they are still dead. I am normally not an easily spooked person, but I might have felt a little spooky if I had visited their graves on Halloween night. YIKES!