I hope this may be my man... he was living in Andrew County (Fillmore is in that county) in 1860 and, according to his obituary, he served in three separate cavalry units (the 5th MSM, the 12th MSM & the Andrew County Battalion Company B)...
the Missouri Digital Heritage site has listings for 32 "S Cooper" soldiers from Missouri.
I have to try to find out which units were issued Starr DA Army revolvers.... any idea if there are ordnance reports for the MSM or EMM?