Incorporating fixed sights and a round-butt frame, and available in .357 Magnum, .38 Special, .38 S&W (.38-200), and 9mm Luger, the Speed-Six was intended for use by plainclothes detectives and others desiring a more concealable handgun.
The standard barrel lengths available for these models were the same as those for the Service-Six, but also included a 3-inch length in certain law-enforcement contract orders, such as for the U.S. Postal Service (Model GS33-PS).
 The .357 Magnum, three-inch barreled model was standard issue to Special Agents of the former U.S. Immigration and Naturalization Service as well as Patrol Agents of the U.S. Border Patrol working plain clothes assignments until both agencies adopted .40 caliber semi-automatic pistols.
 The .38 S&W variant (in England known as the .380 British or .38-200) was equipped with a military-style lanyard ring, and was sold to law enforcement organizations in India.
The .357 Magnum version was standard issue for the Royal Ulster Constabulary, who, unlike most police officers in the United Kingdom, were routinely armed.
Incorporating fixed sights and a round-butt frame, and available in .357 Magnum, .38 Special, .38 S&W (.38-200), and 9mm Luger, the Speed-Six was intended for use by plainclothes detectives and others desiring a more concealable handgun. The standard barrel lengths available for these models were the same as those for the Service-Six, but also included a 3-inch length in certain law-enforcement contract orders, such as for the U.S. Postal Service (Model GS33-PS).  The .357 Magnum, three-inch barreled model was standard issue to Special Agents of the former U.S. Immigration and Naturalization Service as well as Patrol Agents of the U.S. Border Patrol working plain clothes assignments until both agencies adopted .40 caliber semi-automatic pistols.  The .38 S&W variant (in England known as the .380 British or .38-200) was equipped with a military-style lanyard ring, and was sold to law enforcement organizations in India. The .357 Magnum version was standard issue for the Royal Ulster Constabulary, who, unlike most police officers in the United Kingdom, were routinely armed.
Ruger Security-Six