I would not call it a fake. It was most likely made for the 1960's Centennial of the Civil War. There was a similar design, CS oval with stars but only made in cast brass. The stamping is wrong for an original, the letters are wrong for an original and they just didn't have hooks like that.
HOWEVER, that said, it is a relic (most likely) from the Civil War Centennial 1961-1965. As a young'un I participated in some of the reenactments back then. Still a nice find, and you can proudly box it up with some real minie balls for a nice display. Best guess is an old reenactor used it as a belt buckle and lost it hunting or such.