What revolver is this?

Few people will understand what you are talking about if you mention Colt's Revolver-Carbine. Anyway, this revolver is quite a well-known weapon, it's just widely known by its popular nickname "The Buntline Special". Wyatt Berry Stapp Earp, one of the most famous American gamblers, is always associated with this gun.

The "Special" has a unique story. While an unknown number of extra-long-barreled "Peacemakers" with standard frames were produced by Colt before World War II, purists reserve the "Buntline Special" designation for the 31 pistols in the serial number range 28,800 to 28,830. The reasoning behind this is that these guns bore special frames that were manufactured for use with oversized barrels in 1876, the very year dime-novelist E.Z.C. Judson - who wrote under the pen-name of "Ned Buntline" - presented an extra-long-barreled Colt .45 to each of five Dodge City lawmen, according to Wyatt Earp's biographer, Stuart Lake. The gifts were allegedly given in gratitude for "color" the lawmen provided for Buntline's yarns.