The Leech & Rigdon is one of the 1851 Colt copies that was made for the Confederacy.
According to the book CONFEDERATE HANDGUNS by William Albaugh, III, Hugh Benet Jr. and Edward Simmons
"...the products of Thomas Leech and Charles H. Rigdon are ...among the best that were made in the South and, except for minor variations, they all conform to type. They closely resemble the Colt Navy model of 1851 from which they were copied. The major difference was their "dragoon type" barrel, made part round instead of fully octagon because it took less time to produce and was easier to assemble.
All are six-shot, .36 caliber, with iron frames and brass backstraps and trigger guards. Most are stamped Leech & Rigdon CSA on top of the barrel..."
(This book goes into great detail about the history of the company that made these guns.)
Flaydermans Guide confirms that the Leech & Rigdon had a "...casehardened frame, brass guard and backstrap left bright." which is unlike the brass framed Confederate guns made by Griswold & Gunnison, Schneider & Glassick and others.
These guns were originally made in Columbus, Mississippi and Greensboro Georga. About 1500 of them were produced.