The following is based on Van Buren and has not been confirmed by canon sources.
Manufactured by Rheinmetall AG, this 9mm machinepistol is capable of one-handed use for both single shot and burst attacks. Though it is wildly inaccurate, its potential for loads of short-range damage is high.
The Rheinmetall 9mm machine pistol is considered an incredible weapon. With its capability to fire in burst mode, it can mow down anybody that gets close to you. Due to the nature of the battle engine in the demo, that means everybody. Even though you have an infinite supply of ammunition, remember that the gun still needs to be reloaded.
Unused models and icons in the tech demo's files indicate that it could be modified with an extended magazine, a silencer, a suppressor, or a combination of silencer/suppressor and an extended magazine.
Taken from a shelf in the red building on the east side of main street, in the Van Buren tech demo.
While the modified variants don't appear in the Van Buren tech demo, they are still present in the game files and can be spawned with the following console commands, but they remain as non-functional weapons.