Please believe me, I get no pleasure at all in having to tell you it is 100%-certainly a reproduction CSA button.
1- The lines inside the letters are "wrong."
2- All of the Originals had a "perfect circle" loop on the back -- not a U-shaped loop like on yours.
3- The detail on the front is weakly stamped instead of sharp like on an 1861-1865 Original one.
(All of the Original brass 2-piece CSA buttons were manufactured in Britain, very high-quality workmanship.)
Yours has the S&S Firearms civil war Reproduction-buttons type of loop and back with two indented circles, seen in the "backs" photo here, top row second from the left. Confederate buttons, S&S Firearms