This rifle is fairly typical of schuetzen rifles made by George Beuttenmuller. There are two such rifles pictured in my book,GUNMAKERS OF ILLINOIS 1683-1900, Vol. I on pages 67 and 68. The trigger guard on this one is similar, but different. Note that the forward extension on the trigger guard also serves as a palm rest. I have a jaeger rifle by George Beuttenmuller, Chicago, that is relief carved and has a wooden trigger guard. I have never measured the twist in any of his Schuetzen rifles, but I do have one by one of his competitors, R. Grimm, Chicago, that is one turn in 22 inches, definitely a bullet gun. I would guess that this one is similar.
George Beuttenmuller first appears in Chicago City Directories in 1853. His first shop was at 44 LaSalle Street. Subsequent addresses were 178 Washington Street, 1854 - 1861; 180 Washington Street, 1862-1863; 188 Washington Street, 1864-1867; 116 Wells Street, 1868-1871; 89 West Randolph Street, 1872-1874; 151 West Randolph Street, 1875-1880; 78 5th Avenue, 1888; and 155 Randolph in 1893.
The 1860 census lists him as a gunsmith in the 4th Ward, City of Chicago. He was then 39 years old, born in Wurttemberg, Germany. He owned real estate valued at $200. In 1870, he had no real estate value listed, but his personal estate was valued at $10,000. He was a member of a loosely organized group called the "Burger-Schuetzengesellschaft" that shot along the lake-shore, during the 1850's. They were officially organized as the Chicago Schuetzenverein in June of 1863.
George Beuttenmuller had a younger brother, Frederick Beuttenmuller,Sr., who made very similar rifles in Joliet, Will County, Illinois.