The entire Mark XIX Component System is based on a single platform. With its gas operation, rotating bolt and all-steel construction, this is the heart of the fi rearm. Once you?ve purchased a Mark XIX Desert Eagle Pistol, you can change the barrel length or the caliber in seconds, if you have the appropriate Mark XIX components on hand.The Mark XIX (Mark 19) Desert Eagle Pistols offers true interchangeability. Six different pistols are available – .357 Magnum, .44 Magnum or .50 A.E., each with a 6-inch (standard configuration) or a 10-inch barrel that is available as an option in black only. Purchase one pistol and you have the platform to build the other five with a simple switch of components (barrel, magazines and in some cases the bolt assembly). The Mark XIX Desert Eagle .50 A.E. pistols are convertible to the .44 Magnum by simply switching the barrel and magazine (can be done in seconds!). For converting to the .357 Magnum you need to switch the bolt assembly, barrel and magazine (takes a few minutes).