Heckler & Koch UMP

The UMP was designed in the 1990s by Heckler & Koch (HK), as a cheaper, lighter alternative to the MP5, which made heavy use of polymers. The UMP first entered production in 2000. It was designed primarily for use by American military and law enforcement units, as the MP5 was not available in .45 ACP, a calibre which was popular in the United States, but not in Europe. Despite the UMP's improvements and reduced cost, it did not replace the MP5, which ended up outselling the UMP.

Recall

In 2000, Heckler & Koch recalled certain UMP and USC serial numbers due to faulty operating handles. The faulty polymer handles could break off, rendering the UMP and USC inoperable.

The UMP is a blowback-operated, magazine-fed submachine gun that fires from a closed bolt. The closed bolt design increases the accuracy, which is particularly desirable in a law enforcement context. However, the simple blowback design of the UMP makes it less controllable than the MP5.

The UMP was originally designed for larger cartridges such as the .40 S&W and .45 ACP, to provide more stopping power against unarmoured targets, with slightly lower effectiveness at longer ranges. A larger cartridge produces more recoil and makes it harder to control in fully automatic fire. To mitigate the excessive recoil, Heckler & Koch designed the UMP to have a cyclic rate of around 600 rounds per minute, though the rate of fire increases up to 700 rounds per minute if (+ P) ammunition is used for the UMP45 and 745 rounds per minute for the UMP40.

The UMP9 (the 9×19mm variant of the UMP) is almost 0.2 kg (0.44 lb) lighter than the MP5. It has a cyclic rate of around 600-750 rounds per minute. Its predominantly polymer construction reduces both its weight and the number of parts susceptible to corrosion.

The UMP is 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. When the last round of the UMP is fired, the bolt locks open, and can be released via a catch on the left side. The iron sights consist of an aperture rear sight and a 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 bottom of the handguard) for mounting accessories such as optical sights, tactical lights, or laser sights. Vertical foregrips can be attached to the bottom rail for better control during burst and automatic fire.

The UMP can be converted between three different calibres:

• The UMP9, chambered in 9×19mm Parabellum
• The UMP40, chambered in .40 S&W
• The UMP45, chambered in .45 ACP

Apart from their different chamberings, all variants feature the same basic design. The notable exterior difference is that the UMP9 uses a curved magazine, while both the UMP40 and UMP45 use a straight magazine. All three variants of the UMP can be cross-converted to any of the three calibres by replacing the bolt, barrel, and magazine.

USC

The Heckler & Koch USC or Universal Self-loading Carbine is a semi-automatic-only variant of the UMP designed for civilian use. It was created following the Assault Weapons Ban of 1994 in the United States and was introduced in 2000. Changes from the original UMP include a "thumbhole" type stock/grip instead of the pistol grip of the UMP, a longer barrel without the flash suppressor, a magazine limited to 10 rounds, and a semi-automatic-only trigger group and action. Originally available in grey, as of 2008 the USC came only in an all-black finish.

Production of the USC was halted in 2013. In 2018, Heckler & Koch announced a limited production run of the USC.

Clones

• Omega Gideon Shadow, American clone of the UMP released in 2017.
• Tommy Built Tactical TMP/KSM, American clone of the UMP.
• DefGunz DEF9, American clone of the UMP receiver released in 2024.
• S5 Tactical SMP, American clone of the UMP receiver released in 2025.