Agree it is the Michigan Strong. I asked Robles if I could use these pictures in the 2nd edition of Michigan Gunsmiths on which I'm now working. So far have heard no objections. Here is an exerpt:
Strong, William K., Big Rapids, Bay City 1872 - 1884 (reference Sellers, Gardner and Mich State Gazetteer for 1875, R.L. Polk)
Mecosta and Bay Counties. Bay City 1875 "gun smith, State, Upper Big Rapids". Jon Stamp, of Rockford, has done extensive research on W.K. Strong. Material abstracted from his work is presented here. Strong made percussion guns, including over/under rifle/shotguns, using a mule-ear side lock. One of the rifles used a barrel marked ENTERPRISE—JAMES BROWN & SON—PITTSBURG—. The 1880 census shows William K. Strong, Big Rapids, age 70, gunsmith, born in Connecticut, with wife Kittie A., age 48, born in New York. Their adopted daughter Delia, 18, was apprenticed to a dressmaker in the city. Two younger children in the household, John G.13.and a boy ?Alphia?, 11, were both born in Indiana. In November 1883 William K. Strong married a Susan B. Pitcher Miller, in Reed City, Osceola County.