This photograph intrigues me. The uniform, with the exception of the belt plate (which does not appear to be a "US" regulation), is an 1880s period Infantry garrison uniform. The Chasseur pattern kepi was not reg. until 1872, the crossed rifles insignia (as someone else pointed out) wasn't reg. until 1875. The 1872 pattern "five button" sack coat does not appear to have branch color piping on the collar and cuffs: the piping was dropped in 1883. The fore and aft creased, sprung bottom trousers are correct for the 1880s. The problem is the rifle and the bayonet frog. Both are Civil War era. Although the lock and hammer are not clearly visible, Indian War era .45-70 "Trapdoor" breach loading Springfield's had only two barrel bands. The bayonet frog was of a swivel design with a distinctive brass rosette. I suspect the rifle, belt and bayonet (w/ scabbard) are props of the photographer's purchased surplus after the Civil War. The young private in the photo is perhaps home on leave before reporting to his first post (and would not have any weapons with him} and went to a photographer's studio to have a portrait made.
To Join the Company of Military Historians click here