Heckler & Koch HK MP5SD

History

The superior performance of the original Heckler & Koch HK MP5 series drove the need for special pressed forms for use by agents around the world. This eventually became the MP5SD series of submachine guns released in 1974, which featured an integrated suppressor assembly above the barrel that blended perfectly with the shape of the receiver. Sub-variants allow for a different stock (or no stock) and retain all other MP5 features.

The MPSD name is derived from the German "Machine Pistol 5, Muffler". Like the MP5 before it, the MP5SD series fires the widely accepted 9x19mm Parabellum pistol cartridge from a 15- or 30-round detachable magazine.

The main feature of the MPSD series is the large aluminium suppression assembly mounted to the front of the weapon and is fitted with a supersonic 9mm cartridge. Inside this assembly is a shortened barrel that is perforated with about 30 ports to control the escape of gas as the firearm is in motion. As such, the silencer wraps around the perforated barrel assembly and is constructed using a two-stage, dual-chamber process. Surrounding the barrel in the intended manner is the first chamber (the one closest to the receiver) that initially collects the expelled propellant gas and controls the effect of the expelled bullet by reducing its pressure and delaying its acceleration.

The second chamber (before the muzzle) then further eliminates these gases and their effects by increasing the volume of the gas and lowering its temperature while allowing it to escape slowly. The end result is that the subsonic bullet leaves the muzzle at a reduced, now subsonic velocity, so it has a reduced audible signature. Since the MP5SD does not use subsonic ammunition in conjunction with its silencer, it is not a truly "silent" weapon in the accepted sense.

However, a slight latch assembly is housed inside the device, helping to reduce the audible signal of internal action.

Like other variants of the MP5 line, the MP5SD series has a small number of variants based on the original design. The MP5SD1 was the first to be silent and lacked the butt (the end plate mounted in its place) when using the standard semi/automatic fire selector. The MP5SD2 comes with a sturdy fixed stock and the same trigger group as the MP5SD1. The MP5SD3 is stock collapsed, but otherwise identical to the previous SD1 and SD2.

The MP5SD4 is out of stock, but has introduced bursts. The MP5SD5 is similar but has a full solid stock. The last SD model in the series became the MP5SD6, with a foldable stock and triple-round burst capability.

The U.S. Navy ordered a special version of the MPSD3, designated "MP5SD-N", and was given a collapsible stock, "Navy Trigger Group" (visual bullet, not the original "SEF" letter designation). Larger stainless steel muffler (from Knight's Armament Company) and a tritium illuminated front sight.

This version (foldable stock - MP5SD-N1 and fixed stock - MP5SD-N2) is used by SEALs and SAS personnel.

Specification

Roles

Dimensions

Performance

Changes