The Sig P226 was designed for entry into the XM9 Service Pistol Trials (see also Joint Service Small Arms Program), which were held by the US Army in 1984 on behalf of the US armed forces to find a replacement for the M1911A1. Only the Beretta 92F and the SIG P226 satisfactorily completed the trials. According to a GAO report, Beretta was awarded the M9 contract for the 92F due a lower total package price. The P226 cost less per pistol than the 92F, but SIG’s package price with magazines and spare parts was higher than Beretta’s. The Navy SEALs, however, chose to adopt the P226 later.
Schweizerische Industrie Gesellschaft is a Swiss company and Swiss law severely restricts the export of firearms. Consequently, SIG entered into an agreement with German gun manufacturer (and eventual owner) J.P. Sauer & Sohn to facilitate an export market for their products. For the U.S. military XM9 trials, the P226 was imported by SACO. Interarmstook over importing when the pistol was introduced for civilian sales. SIG-Sauer eventually founded SIGARMS, Inc. in the United States, to handle importation of their products. In 2000 the SIG Holding AG sold J.P. Sauer & Sohn GmbH to two German businessmen. The brand name SIG Sauer remained at the J.P. Sauer & Sohn GmbH.
The P226, like the other members of the SIG Classic family, operates by the locked breech short-recoil method pioneered by John Browning. On firing, the slide and barrel are locked together for a few millimeters of rearward movement, after which the barrel is cammed down at the rear. By this time the bullet has left the barrel and the pressure has dropped to safe levels, whereupon the slide completes the rearward stroke, ejecting the spent cartridge. The recoil spring then propels the slide forward, stripping a round from the magazine and in the last few millimeters of forward movement the barrel is cammed upwards, locking the slide and barrel together again.
Instead of the locking lugs and recesses milled into the barrel and slide of other Browning type weapons (such as the Colt M1911A1,Browning Hi-Power and CZ 75), the P226 locks the barrel and slide together using an enlarged breech section of the barrel locking into the ejection port. This modified system, which was devised by SIG, has no functional disadvantages compared to the original system, and has since been copied by numerous firearm manufacturers.
The slide of the pre-1996 P226 was a heavy gauge, mill finished sheet metal stamping with a welded on nose section incorporating an internal barrel bushing. The breech block portion was a machined insert attached to the slide by means of brazing and a roll pin visible from either side. Since 1996, production has shifted to CNC machining and the slide is now milled from a single piece of stainless steel. Therefore the current standard P226 has a black anodized, stainless steel slide. This resulted in a stronger slide, which was necessary to chamber the more powerful .40 S&W and .357SIG cartridges. The frame of all models is made from hard anodized aluminum alloy.
The standard SIG P226 incorporates a decocking lever on the left side of the frame above the magazine release button, which first appeared on the Sauer 38H prior to World War II, which allows the hammer to be dropped safely. In chambering or firing a round, the actuation of the slide automatically cocks the hammer. By using the decocking lever, the hammer can be de-cocked without actuating the firing pin disconnect, making it impossible to accidentally fire the weapon by using the decocking lever. Furthermore, using the decocking lever makes the weapon “drop safe,” which means the firing pin will be blocked from striking a loaded round unless the trigger is pulled. Pulling the trigger and slowly lowering the hammer does not make the weapon “drop safe,” and can result in anaccidental discharge if sufficient force is applied to the hammer. Properly decocked, the pistol can be holstered safely and can be fired in double action mode by simply pulling the trigger. The SIG P226 has no manual safety. Double action trigger pressure is approximately 44 N (10 lbf). Subsequent shots are fired in single action mode with a lighter trigger pressure of approximately 20 N (4.5 lbf). As with other DA/SA pistols such as the HK USP and Beretta 92F, some training is required to minimize the difference in point of aim caused by the different trigger pressure between a first double action shot and subsequent single action shots. The hammer may also be manually cocked at any time by the user to fire in single action mode.