The KGP-9 is a Hungarian submachine gun

Submachine gun

A submachine gun is an automatic carbine, designed to fire pistol cartridges. It combines the automatic fire of a machine gun with the cartridge of a pistol. The submachine gun was invented during World War I , but the apex of its use was during World War II when millions of the weapon type were...

 used by Hungary

Hungary

Hungary , officially the Republic of Hungary , is a landlocked country in Central Europe. It is situated in the Carpathian Basin and is bordered by Slovakia to the north, Ukraine and Romania to the east, Serbia and Croatia to the south, Slovenia to the southwest and Austria to the west. The...

's military forces and prison guards. It operates using a basic blowback

Blowback

Blowback may refer to one of the following:*Blowback *Blowback *Blowback , vacuum effect created in the barrel of a firearm when it is discharged...

 mechanism, and fires the very popular 9mm Parabellum cartridge from an open bolt

Open bolt

A semi or full automatic firearm is said to fire from an open bolt if, when ready to fire, the bolt and working parts are held to the rear. When the trigger is pulled the bolt goes forward, feeding a round from the magazine into the chamber and firing it...

. It is assembled from pressed steel, reinforced with castings. The KGP-9 fires with a hammer

Hammer (firearm)

thumb|150px|Hammer with an integral [[firing pin]] on a [[S&W Model 13]] revolver The hammer of a firearm was given its name for both resemblance and functional similarity to the common tool...

 mechanism and with a floating firing pin

Firing pin

A firing pin or striker is part of the firing mechanism used in a firearm or explosive device e.g. an M14 landmine or bomb fuze. Firing pins may take many forms, though the types used in landmines, bombs, grenade fuzes or other single-use devices generally have a sharpened point...

 contained in the bolt, and is capable of a firing rate of 900 rounds/min.

An interesting feature of this gun is that the standard issue barrel

Gun barrel

A gun barrel is the tube, usually metal, through which a controlled explosion or rapid expansion of gases are released in order to propel a projectile out of the end at a high velocity....

 can be replaced by a longer one, turning the gun into a carbine

Carbine

A carbine , from French carabine, is a longarm similar to but shorter than a rifle or musket. Many carbines are shortened versions of full rifles, firing the same ammunition at a lower velocity due to a shorter barrel length....

 with longer range than a submachine gun. A civilian variant exists, capable of semi-automatic fire only.