Your friend's rifle was probably made by Silas M. Fleming. He originally worked in western Ohio, Preble County if I recall correctly, then moved a little distance west to Richmond in Wayne County, Indiana, where he was working in 1850. He showed up there in an 1852 directory, and probably worked in Wayne County for some time after that.
We need to see pictures of your rifle if you want an approximate date, and to establish which state it was most likely made in. However, his guns didn't change much from Ohio to Indiana. They are distinctive by their "elongated, flattened oval" style of cheekpiece. While his guns were not overly elaborate, he was a very fine workman, and all his guns exhibit quality stocking. A few have inlay work. I've handled a number of them over the years, and one pistol, all percussion guns. All were signed in finely engraved script. He had two brothers (presumed) who were gunsmiths in the same general area. One, Thomas Fleming, worked slightly earlier and left several full-stocked rifles. Another "J. W. Fleming" has been reported, and all the Fleming rifles by the different makers have generally similar elongated oval cheekpieces. Shelby Gallien