The MP5 is a fully automatic submachine gun (SMG) which unlocks at level 4. It is a good weapon for fast-paced, close-range combat with an accuracy of 49 and speed of 47. It has a 30-round magazine size so, like with any SMG, you need to be careful about just spraying a constant hail of bullets at your enemies. That said, this weapon can be upgraded with pack-a-punch to get the MP115 Kollider, which has additional ammo and more damage. So, you’ll go through less ammo, granted that you know how to aim.
The best attachments for the MP5 are the Agency Suppressor muzzle, 9.1” Rifled barrel, SWAT 5mw Laser Sight body, Field Agent Grip underbarrel, 40 Round Speed Mag magazine, Airborne Elastic Wrap handle, and No Stock. You can get an optic attachment to increase the magnification, but this isn’t all that helpful for SMG’s, since most of the gameplay with them is close combat.