OK.....
I have no idea what rifle the "South Carolina Rifle Guard" comes from. Maybe no one living does. Maybe the original caster thought it came off a SC rifle...who knows? No telling.
The Gillespie Guard that Mr. Glazener offers was cast from one off an original 1810 era Mathew Gillespie Rifle. It was the sister rifle to this one.
http://americanlongrifles.org/forum/index.php?topic=8015.0 The sister rifle the guard comes from used a single lock bolt and had more of a V shaped upper forestock. The guards between the two rifles were slightly different but similar. The rifle pictured in the museum as you can see, has wider finials and maybe slightly larger bow and spoon.
The truth is all original forged guards are one of a kind as each was hand made. They may all look similar but each one is an individual.
By far this type of guard is the most pleasing I have held. Shouldering the rifle just feels good and locked in with this guard. Holding a Gillespie really makes me dislike the high grip rail on a Lancaster. "the Bivens style guard"