Case Hardening for Beauty and Durability

Case hardening dates back to the early years of gunmaking as a way to make firearms more durable, accurate and longer-lasting. The fascinating swirls of color were a beautiful aesthetic bonus.

Samuel Colt saw the process as a way to make his company’s guns tougher and stand up to wear, initially using it on hammers, triggers and frames. Other companies like Winchester and Marlin followed suit and embraced the process already used by bespoke European gunmakers. The process can make gun frames pop with colors while other guns provide more subtle coloration.

Rock Island Auction Company has outstanding examples of case hardening in Colts, Winchesters, Marlins and upland sporting arms from across the pond in its Aug. 15-17 Premier Auction that will be shared below, but first we have to answer, what is case hardening?

After more than 130 years, the case hardening on this Winchester 1886 astounds. Produced in 1894, this rifle’s colors leap off the metal like a near-psychedelic dream of swirls and bursts, retaining 98 percent of its finish. This outstanding lever action also has 97 percent of its blued finish on the barrel and magazine tube and slightly more on the breech bolt. The nitre blue of the loading gate is also nearly all present.

What is Case Hardening?

The case hardening process -- sometimes referred to as color case hardening, casehardening or its scientific name, carburizing -- is a heat treatment that diffuses a thin layer of carbon to the surface of gun parts to harden and protect them. Dating back to the 17^th century and earlier when steel was low carbon, the case hardening process simply helped make parts stronger.

After cleaning any grease from the gun parts, they are immersed in iron-rich materials in a closed container and heated in a kiln or oven at high temperatures before dunking or “quenching” the parts in water or oil to rapidly cool them. The longer the parts are heated the deeper the carbon is diffused into the surface of the metal. The vivid colors are a fortunate by-product of the process.

The case hardening colors still swirl on this Winchester Deluxe Model 1886 nearly 135 years after leaving the company warehouse. Beyond its beautiful finish, the gun is chambered for the .50-110 Express and has dovetail blade front sight and four leaf express sight.

Gunmakers generally used bone charcoal in the case hardening process but often changed up the composition by adding leather, hoof shavings or other materials to bring out the colors. As smelting processes improved the quality of steel, case hardening became more of an aesthetic choice.

Gun engravers found high quality steel difficult to work with so modern guns, especially those made by British firms like Purdey or Holland & Holland don’t go through the case hardening process until after they’ve been embellished. That is why collectors of American guns like Colt and Winchester may learn from a factory letter that their gun was shipped “in the white,” because they hadn’t gone through a finishing process to make the surface more durable.

Lustrous case hardening compliments the precious metal game scenes on the lockplates of this pair of James Purdey & Sons over/under shotguns. Scroll engraving surrounding the panel scenes is brought to the fore by the finish. The game scenes on both guns feature desert various species of quail inlaid in gold on backgrounds of scrub brush and platinum inlaid cacti.

Bespoke Firearms and Case Hardening

British gunmakers used wrought iron that was soft and easy to machine for parts like lockplates and frames. It was also good for polishing and engraving. A number of London gunmakers note that they entrust a specific gunsmith, Richard St. Ledger of Birmingham, with color case hardening their guns. In the United States, Turnbull Restoration is often mentioned and the company devotes an extensive part of its website to the process.

This Colt “Fitz Special” Single Action Army out of the Charles Marx Collection bursts with blue, purple and yellow from the case hardening process by Turnbull Restoration and is made all the more vivid by the one-piececarved, steer head, mother-of-pearl grips. Marx ordered the gun sent directly to Turnbull Restoration for customization in April, 2013.

Gunmakers say that the process of case hardening is tricky to master. Heating the parts too long can leave them brittle and warped. A finisher makes sure the parts fit together properly and have good tolerances. This is usually done by precision grinding or lapping.

The blue hues from the case hardening process on the lockplates bring out the tight scroll engraving of Gian Marco Sabatti that adorns this magnificent pair of Fratelli Rizzini 16 gauge double barrel shotguns.

Case Hardening Brings Metal to Life

Rock Island Auction has a number of magnificent firearms available in the August Premier Auction that carry rare features but also retain beautiful case hardening, some swirling with colors while others offer more subdued shades but no less attractive bits of flair.

Revolvers provide a smaller canvas to showcase the vibrant colors, like on the Colt Model 1849 Pocket revolver seen below. The case hardened 1849 shows brilliant blues swirling on both sides of the frame.

The deep case hardening colors of the frame, hammer, trigger guard, trigger and loading lever provide contrast to the lighter Charter Oak grips on this Colt Model 1849 Pocket revolver. The Charter Oak was a Hartford, Conn., landmark that at one time served as a hiding place for the Connecticut Charter of 1662. The tree fell in a storm in the summer of 1856.

A Model 1861 Navy Model is already a rarity for its features while retaining 95 percent of its beautiful case hardened finish.

This Model 1861 Navy has a two-digit serial number and fluted cylinder. Case hardening colors swirl on the frame and loading lever as well as the trigger guard and hammer.

The Colt Single Action Army below is chambered in .38 Special and has “A” level factory engraving by Wilbur Glahn.

This Colt Single Action Army revolver’s tan color from the case hardening process along with the hints of blue and purple showcases Master Engraver Wilbur Glahn’s engraving across the frame, cylinder and blued barrel. The revolver is featured in R.L. Wilson’s “The Colt Engraving Book, Volume Two”

The Colt SAA Frontier Six Shooter below is one of the finest known for several reasons, including its high condition blued and case hardened finishes.

The Colt Single Action Army Frontier Six Shooter’s case hardening colors on the frame and hammer offset the brilliant blue finish on cylinder and barrel serve as a worthy canvas for the acid-etched “COLT FRONTIER SIX SHOOTER.

Rifles Shimmer with Case Hardening Colors

Rifle sideplates offer a more expansive platform for the splendid colors created by the case hardening process and this Roger Kurtz-restored Winchester Model 1886 takedown rifle is no exception.

The vibrant case hardening finish of this beautiful Winchester Model 1886 takedown rifle serves as a beautiful backdrop to the Winchester factory-style engraving by John Weyerts that features flowing scrolls on the case hardened frame, hammer and barrel, surrounding a panel scene of a bear similar to a bear engraved on the stock plate of Teddy Roosevelt’s personal Model 1876 rifle that is on display at Sagamore Hill National Historic Site.

The case hardening process can complement firearms embellishment and make it into a piece of usable art as shown by the previous gun and the one below.

This eye-catching Marlin Deluxe Model 1893 takedown rifle’s case hardened finish offers a tremendous platform for the magnificent embellishments by Master Engraver Conrad F. Ulrich. Never before photographed or offered for public sale, this lever action has No. 5-3 game panel scene and oak leaf relief engraving with a pair of moose in the forest in a panel scene on the left side. The subtle swirl of colors nearly appears to provide texture to the flora and fauna across the gun, and allows gold inlaid accents to pop from the metal.

The colors produced through the case hardening process can also stand alone, while also working in tandem with highly figured wood and crisp checkering for a truly deluxe piece.

This rare and fresh Winchester Deluxe Model 1876 retains 95 percent of its case hardening for a truly shimmering look that sets off the beautiful wood and checkering of the pistol grip stock and foreend. Plus the color case hardening is just one deluxe feature to make this a rarity, with one of every nine Model 1876 bore that finish and one in 14 came with set triggers. Only one of every 400 had special wood and even fewer had pistol grips and even fewer yet featured checkered wood.

Color Case Hardening in Presentation Pieces

While plenty of presentation pieces are seen with precious metal plating, case hardening finishes are also offered at times. This John Rigby & Co. Best “Big Game” double rifle was for the Maharaja of Kutch and was also owned by William Feldstein, an avid elephant hunter who was involved in the development of the .700 Nitro Express round.

This John Rigby & Co. double rifle means business. Chambered in .577 Nitro Express, it has beautiful case hardening colors that highlight the tight English scroll engraving. It also accents the attractively figured and checkered pistol grip stock and forend.

A case hardened rifle or shotgun isn’t the only kind of presentation piece as shown by this pair of Colt revolvers presented to Chief of Ordnance James Wolfe Ripley.

These revolvers, a Colt Model 1861 Navy and a Colt Model 1862 Police each retain 98 and 90 percent respectively of their vibrant case hardening colors across the frame, loading lever, hammer, trigger and trigger guards. The Battle of Campeche on the Navy revolver is still crisp. These two models were the last introduced during Samuel Colt’s lifetime.

Case Hardened Guns for Sale

The case hardening process makes each gun’s finish unique with luminous coloring on some and more subtle coloring on others, but they can all be breath-taking in appearance when seen in person. These beautiful examples and many more are available in Rock Island Auction Company’s Aug. 13-15 Premier Auction. Visit on Aug. 14 preview day and experience these iridescent pieces in person.