In the mid-1960s, the Detective Special's and Cobra's grip frame was shortened to the same size as that of the Agent.

The Cobra was produced in calibers .38 Special, 32 Colt New Police, .22 LR, and a rare few in .38 S&W.

The Third Model (2017–present) is offered only as a 6 shot double action/single action revolver in .38 Special (+P Capable) with a 2" barrel.

This model will be offered with a Matte Stainless Steel finish and has an unloaded weight of 25 ounces.

[2] The Colt M13 Aircrewman was an ultra-lightweight version of the Detective Special constructed of aluminum alloy, and made from 1951 to 1957 for use by United States Air Force aircrews.

Within two years of issuance, reports of cylinder and/or frame failure began to plague the Aircrewman and its Smith & Wesson counterpart, the Smith & Wesson Model 12, despite issuing a dedicated low-pressure .38 Special military cartridge, the Caliber .38 Ball, M41 round.

The original Agent weighed 14 ounces and was available only in .38 Special caliber, with a 2-inch barrel and blued finish.

A slightly revised version of the Agent was released in 1973 with a shrouded ejector rod, with a weight of 16 ounces.

The Viper was essentially a 4-inch barreled version of the alloy-framed Colt Cobra in .38 Special.

Introduced in 1977 and only produced that year, the Viper did not sell as well as Colt expected and was discontinued.

[7] In the owners' manual accompanying some post-1972 Cobra revolvers, Colt recommended the use of +P ammunition for 2nd Model Cobra frames only, with the stipulation that the gun be returned to the factory for inspection every 1,000 rounds (compared with a 2,000–3,000 round interval for the 2nd Model steel-framed Detective Special).