The HK 51, contrary to popular belief, is not made by H&K, being a creation of the American Class II manufacturing after-market. The term Assault Carbine refers to a class of weapon that is a hybrid of the assault rifle and the submachinegun. ... Heckler & Koch G41 Heckler & Koch GmbH (H&K) (pronounced [1]) is a German weapons manufacturing company famous for various series of small firearms, notably the MP5 submachine gun, the MP7 personal defense weapon, USP series of handguns, high-precision PSG1 sniper rifle, and the G3 and G36 assault rifles. ... This article does not cite its references or sources. ... This article does not adequately cite its references or sources. ... NATO 7. ... The word calibre (British English) or caliber (American English) designates the interior diameter of a tube or the exterior diameter of a wire or rod. ... There are many cartridges which use 7. ... In firearms terminology, an action is the system of operation that the firearm employs to seal the breech (in a breech-loading firearm), and to load consecutive rounds. ... Roller-delayed blowback is a firearm operating principle, a refined form of blowback. ... Rate of fire is the speed at which a specific firearm or artillery piece can ]] per minute (RPM or round/min), or rounds per second Note that heat and ammunition concerns mean that most automatic weapons are unlikely ever to sustain their cyclic rate of fire for a full minute... A guns muzzle velocity is the speed at which the projectile leaves the muzzle of the gun. ... Metre per second (U.S. spelling: meter per second) is an SI derived unit of both speed (scalar) and velocity (vector), defined by distance in metres divided by time in seconds. ... Feet per second is a unit of speed; it expressses the number of feet traveled in one second. ... A 30-round STANAG magazine. ...

The HK 51 has no real standards but is usually a cut down and modified HK G3 (or its semi-automatic clones the HK 41 and HK 91) and modified to take MP-5 furniture and accessories. It is usually fitted with a collapsable stock. The Heckler und Koch G3 The G3 (G3A3) series battle rifle is manufactured by Heckler und Koch. ... The Heckler & Koch HK41 is a semiautomatic rifle produced by Heckler & Koch for the civilian market in the 1960s [1]. It is not to be confused with the similarly titled, but separate model, Heckler & Koch G41. ... The HK-91 is the semiautomatic version of the HKs G3 chambered for the . ...

Variants

• HK-51A2*: This is an unofficial aftermarket term for a G3A2 (fixed-stock model) with an 211 mm (8.31-inch) barrel.
• HK-51A3*: This is an unofficial aftermarket term for a G3A3 (retractable stock model) with an 211 mm (8.31-inch) barrel.
• Fleming Arms HK-51S*: The HK-51S (Selbslade, or "self-loading") is an aftermarket semi-auto HK41 or HK91 with the 315mm (12.4-inch) barrel from the G3K carbine, a fixed stock, an MP-5 fat "tropical" forend, and a semi-auto trigger group. It looks like an HK 94 pistol carbine on steroids. Civilian models had a 412 mm (16.2-inch) barrel.
• HK-51K*: The HK-51K (Kurtz, or "short") is a full auto G3 or G3K with a 127 mm (5-inch) barrel, a butt cap, and a MP-5K foregrip. It is suggested that the operator use earplugs, tinted eye-protectors and light gloves when firing this weapon due to the report, muzzle flash, and cinders of semi-burnt propellant created by this monster.
• Armtech HK51: The Armtech HK 51 fires the 7.62 X 51mm round. It is a short-end and modified version of the HK G3 redesigned for the left hand.