MP5SD

In the early 1970s Heckler & Koch began work on an integrally suppressed variant of their extremely popular roller delayed blowback submachine gun, the MP5. They designated the new suppressed weapon the MP5SD, ‘SD’ meaning Schalldämpfer or sound suppressor. While all MP5s could be fitted with an external suppressor using the quick detachable tri-lug system this compromised the handiness of the weapon. With this in mind H&K decided to develop a dedicated variant. The MP5SD was introduced in 1974 and utilised an integral suppressor and several other changes including a lightened bolt to ensure reliable cycling.

In 1964 Walther, one of H&K’s main rivals, developed their own suppressors for use with their MPK submachine gun and their P38 pistols. They were the first German arms manufacture to be granted a special permit to allow suppressor production. The MPK’s barrel configuration allowed the suppressor to be used without impeding the weapon’s sights. These were used by West German intelligence agents and may also have been issued to US Special Forces stationed in Western Germany.

Suppressed Walther MPK (source: Silencers, Snipers & Assassins - Truby)

Unlike Walther’s add-on suppressor the MP5SD’s integral suppressor minimises additional length added to the weapon. The MP5SD’s suppressor is also constructed from aluminium to minimise weight and retain the weapon’s balance. The SD’s short barrel was ported with 30 2.5mm ports to bleed off a significant amount of the propellant gases into the expansion chamber of the suppressor which allows the volume of the gas to expand and pressure to drop before passing through the second chamber which contains conical baffles further reducing the weapon’s report. The MP5SD’s shorter barrel and suppressor combination reduces the speed of the round to subsonic velocities. The suppressor reduces muzzle noise to approximately 70 decibels (approximately the equivalent level of sound as a person’s normal speaking voice). One drawback to H&K’s early design was carbon build up inside the suppressor housing and on the barrel would cause the suppressor to lock up if not regularly cleaned.

Tilo Moeller & Guenter Kaestner’s two stage suppressor design for H&K (source)

The MP5SD quickly gained favour with Tier One special forces units such as the SAS and SBS, Delta Force and the US Navy SEALs and has been adopted by military and security forces around the world. Not only does the suppressor reduce the sound of the weapon firing it also dissipates its muzzle flash. Since its launch in the mid 1970s there have been six incarnations of the SD with various stock setups and trigger groups. The MP5SD continues to be used by militaries and police forces around the world. 

Sources:

Images: 1 2 3

'Handfeuerwaffe mit Schalldaempfer (Handgun with Suppressor)’, Moeller & Kaestner, 10/07/71, Patent No: DE19671553874 (source)

Jane’s Infantry Weapons 1983-84, I.V. Hogg (1983)

The MP5 Submachine Gun, L. Thompson, (2014)

Silencers, Snipers & Assassins, J.D. Truby (1972)

Heckler & Koch MP5 Owners Manual, c.1990s (source)

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