Patricia,

While I don't know of anything focused on the 12th SC, there are a few books you may find useful.

First:

Caldwell, J. F. J. The History of a Brigade of South Carolinians, Known First as “Gregg’s,” and Subsequently as “McGowan’s Brigade.” King & Baird Printers, Philadelphia, Pa, 1866.

Caldwell's book is a classic, and besides brigade level info, includes some things specific to the 12th SC.

There is also a history of the sharpshooter battalion of McGowan's brigade, written by the man who commanded it:

Dunlop, Major W. S. Lee’s Sharpshooters; or, The Forefront of Battle. Tunnan & Pittard, Little Rock, Ark., 1899.

Top men from each of McGowan's regiments were assigned duty in the brigade's sharpshooter battalion in the spring of 1864. I don't think the existence of the battalion was ever formally recognized by the Confederate government, and I think the men remained on their home units' rosters. I am not familiar with the organization of South Carolina's records, or where (or even if) a separate roster of the sharpshooter battalion is maintained.

I think there are reprints of both of these works, but they can be difficult to find. I downloaded free copies of both of them at google books. Go to

books.google.com

and search for the books there.

Best regards,

Andrew Johnson