The well-known "brass" handguns were actually made of bronze
By E. Dixon Larson, American Rifleman January 1968
Colt bronze-frame handguns-sometimes referred to as brass-frame models-were actually made of bronze. Undoubtedly bronze was selected by the Colt firm in an effort to reduce manufacturing costs. Raw materials needed to produce bronze were more abundant than those required for iron, and the bronze alloy, because of its lower melting temperature, was easier to produce than iron.
The bronze castings were easier and less expensive to machine than iron castings, and structural strength was not an important consideration because of the small powder charges of the cartridges utilized in these models.
Another advantage of using bronze was the elimination of the necessity to apply a base plating prior to nickel-plating. This gave a considerable saving since 3 out of the 5 models manufactured were nickelplated.
The Colt bronze-frame arms can be categorized into 5 basic models: the 4-shot House Pistol, often called the "Cloverleaf"; the 5-shot House Pistol; the No. 3 single-shot Deringer; the 7-shot, cal. .22 open frame model; and the 7-shot cal. .22 solid-frame model.
Colt introduced the bronze-frame models in 1872, simultaneously with the final inventory sales of the cartridge conversions and introduction of the new single-action model. This was Colt's attempt to satisfy the demand for smaller-sized handguns and to capture the competitive market. At this time other small alloy-frame single-shot models were being manufactured by such companies as Marlin, Merwin & Bray, Allen, and Moore. An old catalog issued by James Bown & Son of Pittsburgh lists the Colt No. 3 Deringer as "Colt's Never Miss" at $12 per pair, and the 7-shot open-frame cal. .22 at $5 in half plate and $6 in full plate.
Most early advertising indicates that the models were furnished with nickleplated frames, and not in the original bronze state unless requested. To produce such bronze-frame arms today would be extremely expensive and impractical. Some current manufacturers have simulated the old frames by alloy plating of steel or they have utilized brass alloys.