It's from some old lever rifle in .38-55 Winchester; UMC is Union Metallic Cartridge, AKA Remington.
The S and the H stand for "Solid Head"--they type of bullet used.
Loaded, it would have looked something like this one: http://www.gunauction.com/buy/100567...s.h.-headstamp
Anti-intellectualism has been a constant thread winding it's way through our political and cultural life, nurtured by the false notion that democracy means that "my ignorance is just as good as your knowledge".--Isaac Asimov
There are no dangerous weapons; there are only dangerous men.--R.A.H.
..Man fights with his mind; his weapons are incidental--Jeff Cooper