Sub-machine Gun (or SMG) is an automatic carbine designed to fire pistol cartridges. They are primarily used by police forces and military special forces for close quarter fighting because of their small size, light profile, and pistol caliber bullets that are less likely to over-penetrate objects and cause injuries to innocent bystanders.
Submachine guns are classified as primary weapons in CrossFire. They generally have a high firing rate, moderate accuracy, low recoil, low to medium damage, light weight, and medium-high ammo capacity. They are chambered in different pistol calibers, and vary in size and shape.
SMGs are the common weapons for new soldiers, because most of the sub-machine guns usually have low rank requirements, or even no rank requirements at all. Experienced players often use them for run-and-gun tactics or simply rushing at enemies & drying out the entire magazine.