The Glock 22 is a pistol manufactured by Glock. It is a Glock 17 modified to fire .40 S&W ammunition. It uses a modified slide, frame, .40 S&W barrel and magazine but is otherwise near identical in looks to the Glock 17. It has a 10, 15, or 17 round magazine capacity. One notable feature of the Glock 22, and indeed many modern .40 S&W pistols, is the ability to change the caliber to .357 Sig with a simple barrel swap. This is possible due to the similar operating pressures of both rounds, and the fact that the .357 Sig is based on a .40 S&W case, necked down to accept .355 inch bullets.