PP2000

The PP-2000 is a Russian automatic personal defense weapon developed by the KBP Design Bureau. The PP-2000 weighs around 1.5 kilograms, and is intended for use by SWAT teams, soldiers, and common law enforcement. As of 2009, the weapon is only in the hands of Russian law enforcement groups. An odd feature of the weapon is its 44 round magazine which can be fitted on the butt of the gun to function as a stock. A common wire stock is also available.

SMG vs. PDW

The 9mm cartridge has been around for over a century as the gold standard for pistols and submachine guns, offering respectable power for a case of its size. Unfortunately, with the advent of lightweight body armor, the old Parabellum just doesn't cut it situations where the enemy might be wearing kevlar; 9mm ammo is so ubiquitous that Class II body armor is specifically defined as being "9mm FMJ-proof." PDWs (personal defense weapons) are a recent designation for pistols and SMG's built to compromise lighter forms of body armor, an effect generally achieved by using newer and more advanced bullet designs. 
 
Where Fabrique National and Heckler & Koch used smaller, faster bullets to achieve an anti-armor effect (the 5.7x29 for the P90 and 4.6x30 for the MP7, respectively), the Russian decided the improve the versatility of the PP-2000 by developing a high-powered 9mm round, designation 7N31. This allows the PP-2000 to chamber the more cost-effective 9mm Parabellum where necessary and gives it more stopping power than rival PDWs, though the mass of the round and extremely low weight of the gun make it less controllable than its competitors.