The NJ5-B SMG is a modified version of the NJ4 SMG which has a slower rate of fire but more damage per shot. It also has the ability to fire while scoped, offering the Raider a new longer-range option. It deals 125 damage per hit at medium range. This weapon excels as a finishing weapon, but works very well as a skirmishing weapon as well, if one is confident in hitting most of the shots. Compared to other automatic projectile weapons, the NJ5-B has a very large projectile, which makes is a bit easier to land shots on target.
Compared to the other automatic weapons available to the Raider, the NJ5-B is arguably the most versatile. It's damage-per-second (DPS) and projectile size make it easy to deal large amounts of damage very quickly. While the NJ4 may be slightly better against light and medium classes in skilled hands, the NJ5 is generably better for the average player. See link below for a detailed comparison of all the Raider's automatic weapons.