Simon Miller or S. Miller was an Upper Susquehanna School gunmaker.
I believe it to be original flint. Overall length 58” it is approximately .40 Caliber, smooth at muzzle. Unknown further down
Barrel is slightly tapered. Approx .850” at breech, .700” at muzzle. Hooked breech, take-down style stock. Pictured in The Pennsylvania-Kuntucky Rifle, by Kauffman.
RCA dimensions:
C: 13”
D: .850”
E: 1.475”
F: 4 3/16”
G: 1.5
H: 1 1/16”
I: 1 1/4”
J: 1 3/8”