You have a Colt Model 1892 U.S. Army service revolver. R.A.C. was Rinaldo A. Carr, a U.S. Government Inspector who worked at Colt's from 1889 to 1909.
The Colt serial number is the one located behind the crane, and indicates the revolver was made in 1894. The number on the butt is the Army's number, and there should also be U.S. Army and a Model date on the butt.
The gun was originally blued, chambered in .38 Long Colt, and had a 6" barrel with plain walnut stocks. It was also the first double-action/hand ejector revolver to be adopted by the U.S. Army. Some were still in service as late as World War Two.