Smith & Wesson "N" to the largest .44 Magnum type frame. In 2003, the even larger "X" frame was introduced for the .500 S&W Magnum. Most Smith & Wesson revolvers have been equipped with an internal locking mechanism since the acquisition by Saf-T-Hammer. The mechanism is relatively unobtrusive, is activated with a special key, and renders the firearm inoperable. While the lock can simply be left disengaged, most gun enthusiasts prefer "pre-lock" guns. In 1953 the U.S. Army was looking for a pistol to replace the Colt 1911A1. To obtain a bid from the U.S. Government, Smith & Wesson began working on a
Smith & Wesson SD built, the unique feature was a Titanium slide. The SW40Ti was never put into production. At this time Smith & Wesson retired the 4.5 inch barrel and switched all Sigmas to the 4.0 inch barrel. Sigmas from this era onward are considered "2nd generation" Sigmas. Shortly after the introduction of the VE series, Smith & Wesson further improved it by adding an accessory rail but did not change the model number to reflect this update. Sometime after 1999 Smith & Wesson introduced the SW40P and SW9P. These models were identical to the SW40VE and SW9VE but added porting to the