@Ferd454231
Major Congratulations on the Palmetto musket..
It's as right as rain, showing the usage that would be expected. I'll post a few more photos, but the link from UCV relics a few postings above will have some good photos of the barrel and butt plate marks on
most, but not all, of the Palmetto long guns.
Wm. Glaze had been working with Benj. Flagg in obtaining 1842 model muskets for SC even before the establishment of The Palmetto Armory. The majority of parts in everything the Armory made were surplus or condemned. The "42 pistols often have small "C" marks on some major parts.
The barrel on your gun is from a US Model 1842 .69 cal., smooth bore musket, assembled by Flagg {with leftover Asa Waters} parts., on an earlier {pre-Palmetto} SC contract. It was US inspected at some time well before it went on to a Palmetto musket, thus the "eagle head" on the barrel.
The bayonet lug on the bottom of the barrel is where it should be, although others are on top. The '42 had no rear sight...again correct. Rear sight's were added much later when these most remaining {all had brass bands} Palmetto muskets were rifled and sighted for the ACW.
The "S.C." on the butt plate is also correct, and could even be over stamped on US, if a surplus US plate was the next butt plate laying on the workbench. When you get to inspect/accept your own production there's more than a little lee way !!
I'll be happy to take her off your hands for the next few years for a thorough evaluation.

BTW, it's in better condition than most of 'em.
Muzzle area of 1842 Flagg. Bottom bayonet lug...some are on the top.
Breech area of same. Note the "Eagle". My bar code is the "15" I've had this one a very long time..(1063 now)
SC buttplate. fresh stamp on a surplus 1842 buttplate