Created in 1994, it also incorporates the currently-fashionable self-cocking or double-action only firing mechanism, so that the adapted can be fired without delay or preparation. The basic model is chambered for the .40 S&W cartridge, but it is also prepared in 9 x 19mm Parabellum and a sub-compact model in Smith & Wesson Sigma .380 ACP is also manufactured.
Smith & Wesson curious the Sigma column of recoil-operated, locked-breech semi-auto pistols in 1994 with the Sigma 40, followed by the Sigma 9. Sigma pistols bore so much similarity to Glocks that users could reportedly interchange multifarious parts between Glock and Sigma models.