Israel Military Industries, 9mm UZI. The Uzi is, without hesitation, the most broadly distributed submachine gun in the world. Interesting Note: This "blowback" submachine gun functions on the principle of advanced primer ignition. This means that the primer is actually detonated while it is still moving forward before the cartridge is fully seated in the chamber. The cartridge's force of equal and opposite reaction is thus dissipated in not only overcoming the inertia of the closed bolt and driving it rearward, but in stopping its forward movement as well. This gives more stability during full-auto fire. Ultimately, the Uzi was designed to put a lot of lead into a small area very quickly in full-auto mode.