The Skorpion submachine gun is available in both Metal Gear Solid 3 and 4, but you might know it best as the free submachine gun in Metal Gear Online. When you're playing with Drebin points on, this is the gun that you're forced to use when you have no points acquired. Read more about the Skorpion after the break.
Allow me to get this out of the way first: the gun featured in Metal Gear Solid 4 and Metal Gear Online (not sure about MGS3) is the vz. 83, which is a variant of the traditional 61, which I'm going to be talking about in this article.
The Skorpion is a Czechoslovakian 7.65mm submachine gun. It was developed in the sixties by a man named Miroslav Rybar and produced by the esk� Zbrojovka arms factory in Uhersk� Brod, a town in the Zl�n Region of the Czech Republic. In 1980, Yugoslavian Crvena Zastava factory (currently known as Zastava Arms) acquired the production rights to manufacture the gun and starting producing them as the M84 and the M84A. Unlike the original version, the M84 used a synthetic pistol grip. The M84A was a semi-automatic variant made for civilians.
Due to its small size and short magazine (10 or 20 round), the Skorpion is carried in a leather holster like a traditional pistol. It can also be fitted with a sound suppressor.
The Skorpion is currently used by the armed forces of the Czech Republic, Slovakia, Angola, Croatia, Egypt, Iraq, Libya, Mozambique and Uganda.
The vz. 83 variant, which is featured in Metal Gear Solid 4: Guns of the Patriots and Metal Gear Online, was designed in the ninties and uses the 9x17mm Browning Short cartridge.
Source: Wikipedia