The sale itself is being held in Dallas, Texas, while online bidding will draw firearm collectors from further afield.
Among the highlights is this Model No. 5 Paterson Revolver, with 9-inch barrel and attached loading lever, whose bids are open at $350,000.
The .36 caliber weapon "with stagecoach holdup roll scene" has the world "COLT" emblazoned within its border motif, and a 9-inch octagonal barrel.
Of note is the rarity of the gun's German silver-made band inlays. The use of German silver in Texas Paterson revolvers is confirmed by R.L. Wilson's, The Paterson Colt Book.
Through an examination of the famous Dennis A LeVett Collection, the book notes that only three Texas Paterson revolvers appear with band inlays, without hand engraved decoration - including this model, Serial Number 515.
One reason that Texas Paterson Colt revolvers are so seldom observed today is that only 150 were bought by the US government for the Navy, with a further 180 examples bought by the Republic of Texas for its Navy.
Several of the latter were subsequently issued to Texas Rangers, and were given hard use on the frontier.
Historically, the gun was a predecessor to the Walker Colt - and both are extremely important in the evolution of Colt firearms and the evolution of repeating hand and long guns.
Due to its historical importance, No. 5 Paterson's have been much sought-after by museum collection, including The Metropolitan Museum of Art, The New-York Historical Society, and the Smithsonian Institution's National Museum of American History.
Each of these factors contribute to the gun's $350,000-plus value - and it will certainly be one to watch in Heritage's ongoing internet sale. Online bids close on September 17.
- Click here to view our Medals and Militaria for sale
- Learn how you can get pleasure and profit by investing in antique firearms
- Read all the latest Medals and Militaria news