Ancestry.com now has the National Archives "U.S., Returns from Military Post, 1806-1916" (by Post location State/Territory- and Post name) In them are not only the muster rolls but commanding officers reports. These are details not found in the O.R. I now have insight into what was going on with the garrison at Fort Moultrie prior to Major Anderson's arrival. There are minute details of the duties of each officer and the duties of the garrison by month over decades. The only drawback is it is they are images of original reports, hand written and they have to be transcribed.