Next, Submachine Guns.

A submachine gun is, in the basic of terms an automatic weapon that fires a pistol cartridge. In WWII they served as a great main-arm; Russians had entire regiments armed with subguns and the rate of fire they could produce was nothing short of tremendous.

Unfortunately, Submachine guns as a main military arm didn't last long. Spec-Ops and Covert forces still use SMG's. But most people use Carbines for close combat duty these days. But they are still used by Tank-Crews and Navy for defensive purposes.

They have a few flaws, namely they are pretty ineffective against modern body armor. However, certain ammunition types such as the Russian 9x21mm SP-10 are capable of penetrating armor very well. A special type of weapon class which I would consider an SMG is called a Personal Defense Weapon, I'm sure everybody has seen a P90 before. They promote armor penetration for lack of terminal ballistics.

When is the suitable time to use a SMG? Urban conditions; cramped conditions and any time where achieving multiple hits is more important. SMG's are used by police forces such as SWAT and probably any other law enforcement department.

Couldn't think of much on SMG's for now, I'll probably add more whne I do the mega edit.