Hello John,
My first source was my own index card file which listed two 3" Rifles and one Whitworth long range Rifle. I next consulted the book "The Long Arm of Lee". A history of the artillery of the Army of Northern Virginia written by Jennings Cropper Wise, a well qualified person to write on this subject. Lieutenant Colonel Wise was son of ex-Governor Wise of Virginia, graduated from and was later commandant of VMI. He personnally knew many of the military leaders mentioned in the book who provided much of the material. His book is in my opinion, the finest account of confederate artillery of the civil war, and sadly, a source most overlooked by authors. He was a combat officer in the First World War, gassed twice and wounded and finished the war as a Lt. Col. The book is in two volumes and most of the pages providing information is in volume two, pages 510, 537, 538, 618, 619 and many more. You may be confused from the fact that excerpts you may have read may be actually discussing only a detached section of two guns and not the full battery. I have seen this in Wise's book. In early 1864, the battery had two sections, one of two Whitworths and the other section of two Ordnance Rifles. The section of Whitworths commanded by Lt. George A Ferrell was often detached and reported in printed material as "Hurt's battery with two guns". In this manner, the other section of two Ordnance Rifles appear to be dropped when actually they were still with the army with McIntosh's Artillery Battalion. It was common practice to detach sections from a battery for a short temporary task. I also consulted Joseph H Crute,s book "Units of the Confederate States Army" which was little assistance.

Hope this helps
Ron