{{Hebiquote
|quotetext=The promise premise behind this weapon is as follows: A 7.62 NATO machine gun, but [[Heckler & Koch MP5A3|MP5]]-sized. The HK51-B is exactly that, and it is every bit as enjoyable as it sounds - if you enjoy the thought of a short-barreled, fully-automatic 7.62 NATO machine gun thumping against your shoulder, that is. When shooting this thing, it will spit muzzle blasts so big, you'll have your eyebrows singed, and it will be louder than nearly any other weapon in your general vicinity. Is it powerful? Well, with a an 8.9 inch barrel, sacrifices have to be made. Is it short and relatively lightweight? Oh, you bet.
|quoteauthor=Tempest
}}
This weapon is referred to as a '''Specs-docs only''' weapon. It cannot be normally found in the Mazes, and will only be available after completing the following requirements:
* Turn in the following specifications documents to the Proving Grounds engineer, at the [[Calfair Sector ]] workshop:** [[Specs docs]]: ''#FJ051 - 7.62mm caliber heavy barrel specifications cut down to submachine gun length (8.9 inches)''* Bring a * A [[G3A3]] and a an [[HK21]], both of which will be used for conversion into this weapon.** [[File:Parallar symbol.png|10px]]'''175'''
Upon completing the requirements listed above, the engineer will offer a brand new Vollmer HK51 will become available for sale at the Calfair Sector workshop from the Proving Grounds engineer, for -B. The [[File:Parallar symbol.pngM13 ammo belt|10pxbelt box]]'''700'''loaded in the provided HK21 will be loaded into this weapon after conversion. For this reason, this weapon is '''Rarity 7 (Unique)'''. Upon successfully converting a G3 and a HK21 into a HK51B, it will be loaded with the belt the HK21 was loaded with.
Please note that the Proving Grounds engineer is only available during the day shift (between 8 AM and 8 PM).
== [[Maze Customs]] ==
This weapon can receive the following minor customization services:
* '''Vollmer Tactical'''
=== Vollmer Tactical ===
''Yes, even the Vollmer can be tacticooled up. This update package installs a quad-rail system, comprised of a tri-rail on the handguard and an HK claw-to-NATO rail adapter, allowing you to use more common optics.''
Cost: [[File:Parallar symbol.png|10px]]'''500'''
Modifications:
* Optics: Becomes '''NATO mount'''
* Lights: Becomes '''2x Long interface'''
* Underbarrel: Becomes '''Long interface'''
[[Category:Class 1 weapons]]