civilian sale. The M11 is to be replaced in the Army and Air Force through the Modular Handgun System program. On January 19, 2017, it was announced that the SIG Sauer P320 Compact (M18) had been selected to replace the M11 as the U.S military service pistol. One factor in winning the Modular Handgun System competition was the ability to employ 9mm Parabellum, .357 Sig or .40 S&W cartridges within the same basic frame. P229 Introduced in 1992, the P229 is an upgrade to the P228 being an identical compact firearm often used for duty or concealed carry purposes. Developed specifically for the US market and assembled with both German and US-made parts, the P229 features a heavier slide to tolerate more powerful rounds the P228 is incapable of. The standard version features a DA/SA trigger. The pistol has also been made available in a Double Action Kellerman (DAK) model, which is a DAO system with two trigger reset points, and a lighter, smoother pull than that of traditional DAO handguns. Most of the above-mentioned factory variants of the P226 are also available for the P229, including the Equinox option, Elite lineup, as well as a SAS GEN 2 model. The P229 differs from its cousin the P226 in several respects, and was originally introduced to supplement and then replace the P228 by adding the .357 SIG and .40 S&W as available chamberings. The P229 was the first production handgun introduced that could chamber the .357 SIG round. The P226 and P228 were originally manufactured using a stamped-steel slide on an aluminum alloy frame. The P229 consists of a CNC-milled stainless steel slide, typically colored black with a Nitron finish. The P229's milled steel slide was introduced to handle the higher slide velocities created by the .357 SIG and .40 S&W loads, which the stamped slide of the P228 could not handle without the use of a much stiffer recoil spring. This would have made manual slide-retraction much more difficult and the use of a milled stainless slide (coupled with the new milling and stainless production capabilities found in the U.S. factory) with a standard weight recoil spring made more sense. A standard weight recoil spring for the P229 is . A spring weight of or higher would have been required if a stamped slide was used for the .40 S&W or .357 SIG chamberings. The SAAMI maximum chamber pressures