SIG Sauer P226 - Design Details

Design Details

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 block, 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 an accidental 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 lb_f). 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.