Snider-Enfield Mk. III breech-loading conversion Cavalry carbine

Manufactured by Enfield - converted for metallic cartridges as such - in England c.1870, using the 1866 Snider metallic cartridge conversion design of the Pattern 1853 Rifled Musket.
.577 Snider single shot 1864 Tabatière-like action, leather cover on the rear ladder sight, safety cap on the firing pin mechanism linked to the gun by a chain lanyard.

The Snider-Enfield would stay in service as England’s military rifle from 1866 to 1871-73 when it was replaced by the Martini-Henry falling-block rifle, although as per usual rear-echelon troops would still use it up until WW1.

same model without the leather cover and safety

The Pattern 1861 Enfield Musketoon,

While the 1853 Enfield rifle musket served as the primary arm of the British Army in the 1850’s and 60’s, the British Army saw a need for a carbine version of the Enfield rifle.  Introduced in 1861, the M1861 Enfield Musketoon was significantly shorter and lighter than the standard Enfield service rifle.  While shortening the barrel decreased accuracy, this was made up for by incorporating a faster rifle twist in the barrel (1:48) as well as more grooves (5 groove barrel).  The musketoon also was issued with a sword bayonet.

Originally the Enfield Musketoon was issued to artillery units in the British Army.  However, more were produced for export to the Confederacy during the American Civil War than were actually used by British units.  They were used to arm Confederate artillery units, but were also especially favored by Confederate cavalry units because of their ease of use while mounted on horseback.