Heckler & Koch UMP

The UMP (Universale Maschinenpistole, German for "Universal Submachine Gun") is a submachine gun developed and manufactured by Heckler & Koch.

Design details
The UMP is a blowback-operated, magazine-fed submachine gun firing from a closed bolt. As originally designed, the UMP is chambered for larger cartridges than other submachine guns like the MP5. This was done in order to provide more stopping power against unarmored targets, albeit at the cost of a somewhat shorter effective range compared to the 9x19mm MP5. Using a larger cartridge also results in more recoil, making the weapon more difficult to control when firing in fully automatic mode. To counter this effect, the cyclic rate of fire was decreased to around 600 rounds per minute making it one of the slower submachine guns on the market. Such a slow rate of fire makes burst-fire settings superfluous; yet, many users believe the practicality of the 2- or 3-round burst setting to be a desirable feature in a submachine gun.

Despite these shortcomings, the UMP is regarded as a reliable and useful submachine gun. Additionally, the UMP9 (the 9x19mm version of the UMP) is almost 0.45 kg (almost 1 lb) lighter than its MP5 counterpart. It is constructed mostly of polymers, to decrease weight and reduce the number of parts that can become susceptible to damage from corrosion. These polymers stand up well to wear and tear in the field.

The UMP is currently available in four trigger group configurations, featuring different combinations of semi-automatic, 2-round burst, fully automatic, and safe settings. It features a side-folding buttstock to reduce its length during transport. The standard viewing sights consist of an aperture rear sight and front ring with a vertical post. It can mount four Picatinny rails (one on top of the receiver, and one on the right, left, and the bottom of the handguard) for the attachment of accessories such as optical sights, flashlights, or laser sights. Vertical foregrips can be attached to the bottom rail for increased controllability during burst and automatic fire.

The UMP was designed as a replacement for the Heckler & Koch MP5. It was designed to be less expensive and lighter than its older cousin. It is also designed to look, feel, and operate like an MP5 so less or no re-training is required for MP5 operators. While it has proven largely successful in the field, the UMP has not replaced the MP5 as intended, but rather acts as a complement to it.

Variants
There are three versions of the UMP: the UMP45, firing a .45 ACP cartridge; the UMP40, firing a .40 S&W cartridge; and the UMP9, firing a 9x19mm Parabellum cartridge. Apart from the different chambering, all versions feature the same basic design, the most noticeable difference being the curved magazine used on the UMP9. All three versions of the weapon can be converted to any of the available chamberings via replacement of the bolt, barrel, and magazine.

The USC or Universal Self loading Carbine is a semi-automatic version of the UMP that could be owned by private citizens for sporting purposes. It was designed following the Assault Weapons Ban of 1994 and conforms to those standards. Changes from the original UMP include a "thumbhole" type stock and grip (versus the pistol grip of the UMP), longer barrel, limited 10-round magazine, and semi-automatic only trigger group and action. Originally available in gray, beginning in early 2007 the USC comes only in an all-black finish.