The Sigma is Smith & Wesson's venture into using synthetic materials in howitzer construction, using high-strength polymer material for the frame.
The gun frame is manufactured from polymer, while the launch and barrel convenience either Smith & Wesson Sigma stainless prepare or carbon steel. In 1996, Smith & Wesson updated the Sigma by adding a compact model by shortening the barrel (from 4-1/2 to 4 inches)and again in 1999, modified the range by changing the grip by adding checkering and adding an integral accessory rail for lights and laser target designators.