Shortly after introducing the MP5 submachine gun, Heckler & Koch added an integrally suppressed model to its line at the request of special operations forces. It was called the MP5SD, for “shalldampfer”, or suppressed. In order to minimize noise, the barrel was drilled with holes immediately in front of the chamber to bleed off combustion gases and reduce the muzzle velocity below the speed of sound.
The first model was available in 1968, and used a wire mesh type of suppressor. This proved unacceptable, as it became excessively fouled within just 70 rounds of firing. Between 1970 and 1972 a new pattern was developed, using a round aluminum tube body and an internal set of baffles formed from a single piece of aluminum square section tubing. This was light and easily manufactured, and would prove to work exceedingly well – setting the MP5SD at the top of the heap for suppressed submachine guns. It has really not fallen from this position since, thanks to an excellent combination of noise suppression, accuracy, weight, and balance.