I take it that you did not follow the link at the bottom of Ancestry.com's purported "record" page. If you had, you would have found the following:
For copies of the original files write to:
National Archives – Southeastern Region (Atlanta)
4712 Southpark Blvd.
Ellenwood, GA 30294
Phone: (404) 736-2820
BTW, the reference is Petition No. 1521M