The GP100 replaced the Security-Six in the Ruger product line, but the Six line is still a very strong revolver, popular with shooters and collectors today. In the early 1980s, Ruger commissioned a heavier duty upgrade of the Six line that could handle a 'lifetime diet' of full-powered magnum loads, the GP100, which featured a beefier frame and full under-lug barrel, stronger steels, a redesigned grip frame and, most notably, a triple-locking cylinder to give extra strength to the action. While Ruger's Security-Six line has been out of production since 1988, a total of over 1.5 million revolvers were produced and they remain well-liked and respected, as well as highly sought after in the second-hand market due to their strength and reliability. The Security-Six and its derivatives also became the standard issue service weapons of a large number of police departments, in addition many were exported overseas. Various models were issued by US government agencies as diverse as the former Immigration and Naturalization Service, the Postal Service, the Border Patrol, and numerous police agencies. The 'six series' line enjoyed sales success because of their basic features, solid construction, and competitive pricing. The Ruger Redhawk, introduced in 1980 and also designed by Sefried, was a scaled-up and improved version of the Security-Six. Ruger's new double action revolvers were unlike other guns on the market in that they used a one-piece frame, rather than a removable sideplate, which lent them superior strength. The grip profile of the Sentinel was used on the 'Six' line.

Sefried had previously worked for High Standard Manufacturing Company, where he designed the High Standard Sentinel revolver. As with all Ruger firearms, the Security-Six revolvers were robustly designed with large, heavy-duty parts for durability and to allow for investment casting.

Ruger used investment casting for most parts in an effort to hold down production costs.

The corporation's earlier designs had been Colt Peacemaker-style single-action revolvers. The introduction of the Security-Six and its variants marked Sturm Ruger's first attempt to enter the double-action revolver market. Smith & Wesson and Colt at the time dominated the medium frame law enforcement double action revolver contracts. Despite being popular with civilians, Bill Ruger wanted to get into law enforcement and security contracts.

Development and history Īs far back as 1966, Ruger designers Harry Sefried and Henry Into began working on the company's first double-action revolver. These revolvers were marketed to law enforcement duty issue, military, and civilian self-defense markets. The Ruger Security-Six and its variants, the Service-Six and Speed-Six are a product line of double-action revolvers introduced in 1972 and manufactured until 1988 by Sturm, Ruger & Co.

Ruger single six magnum serial numbers