The Heckler & Koch MP5SD

suppressor

The MP5SD's 146 mm (5.7 in) barrel has 30 2.5 mm (0.1 in) ports drilled forward of the chamber through which escaping gases are diverted to the surrounding sealed tubular casing that is screwed onto threading on the barrel's external surface just prior to the ported segment.

The MP5SD's integral suppressor itself is divided into two stages: the initial segment surrounding the ported barrel serves as an expansion chamber for the propellant gases, reducing gas pressure to slow down the acceleration of the projectile.

The second decompression stage occupies the remaining length of the suppressor tube and contains a stamped metal helix separator with several compartments which increase the gas volume and decrease its temperature, deflecting the gases as they exit the muzzle, so muffling the exit report.

The bullet leaves the muzzle at subsonic velocity, so it does not generate a sonic shock wave in flight. As a result of reducing the barrel's length and venting propellant gases into the suppressor, the bullet's muzzle velocity was lowered anywhere from 16% to 26% (depending on the ammunition used) while maintaining the weapon's automation and reliability.

Receiver

The receiver housing has a proprietary claw-rail mounting system that permits the attachment of a standard Heckler & Koch quick-detachable scope mount (also used with the G3, HK33, and G3SG/1).

It can be used to mount daytime optical sights (telescopic 4×24), night sights, reflex sights, and laser sights.The mount features two spring-actuated bolts, positioned along the base of the mount, which exert pressure on the receiver to hold the mount in the same position at all times assuring zero retention.

All versions of the quick-detachable scope mount provide a sighting tunnel through the mount so that the shooter can continue to use the fixed iron sights with the scope mount attached to the top of the receiver.

A Picatinny rail adapter can be placed on top that locks into the claw rails. This allows the mounting of STANAG scopes and has a lower profile than the claw-rail system.

Origin: Germany, 1974

Manufacturer(s): Heckler and Koch

Caliber: 9x19mm Parabellum

Action: Roller-Locked, Delayed Blowback

Rate of Fire: 700rpm

Weight: 6.61lbs

Barrel Length: 5.75 inches