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I Bleed Urban Gray
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Universale Maschinenpistole

Air gun Machine gun Trigger Gun barrel Gun accessory


The UMP is a close quarters battle submachine gun (SMG) designed by HK as the cost-effective replacement for their MP5 series. The UMP is designed to compete by leveraging versatility, light weight, low purchase and maintenance costs, and improved reliability without sacrificing accuracy. Like the MP5, UMP trigger groups come as modular assemblies that can be easily swapped based on agency or mission requirements. Designed to be more mission-configurable than the MP5, the UMP offers the advantage of caliber modularity: being easily interchangeable among 9mm, .40 S&W, and .45 ACP.

The UMP fires from the closed bolt position for accuracy and safe handling. Available in select fire or semi-auto configurations, the UMP includes a bolt catch to hold the bolt rearward when the last round is fired.

While the MP5 relies on a complex roller-delayed action, the UMP, in contrast, was simplified with a straight unlocked blowback system. An injection-molded polymer chassis ensures the 9mm UMP weighs in at 4.63 pounds, making the MP5 appear heavy at 6.47 pounds (MP5A3).


Announced in 1998 and released in 1999, the UMP traces it’s roots through a series of projects in which HK attempted to improve the MP5. In April 1980 HK submitted the Model SMG in response to a solicitation from the Naval Weapons Support Center for a joint service submachine gun. In 1984 HK followed this with the submission of the Model SMGII. As these prototypes evolved, the firing system was simplified from roller-delayed to simple blowback; and the use of polymers grew. By the time the MP2000 prototype was introduced in 1989, 50% of its chassis was injection-molder polymer and it incorporated an integral bolt catch. This was the UMP’s direct antecedent as the UMP design project commenced in 1996.

The UMP’s purpose and design were premised on two key thrusts: First was global versatility, and second was cost effectiveness.

Versatility: In mid 1990s the U.S. military and law enforcement organizations (LEO) were “up-gunning” their 9mm handguns to .40 and .45. USSOCOM introduced the Mark 23 and the FBI’s Hostage Rescue Team and regional SWAT teams switched from Brownings and Sigs to 1911s. HK was even designing a 1911 for Delta Force. HK also noted interest in a .45 SMG from agencies outside the U.S. Meanwhile, nearly every police department in the U.S. was converting their sidearms to .40 S&W. As the MP5 chassis could not accommodate .45 caliber, nor interchange between 9mm and .40, HK moved to design a different platform for it’s new SMG. The design concept was to provide a .45 caliber option for the U.S. military and non-U.S. customers seeking a .45, a .40 S&W option for U.S. LEOs and a 9mm option for European and other global customers. This meant the receiver would be large enough to accommodate the .45 cartridge.

Cost effectiveness: In the 90s U.S. police departments saw consistent increases in operating costs associated with workforce growth and increased deployment of computers and body armor. Many local departments were still transitioning away from revolvers in the early 90s and almost all with 9mm were moving to .40 S&W. This left little budget space for investment in expensive SMGs. HK planners wanted to respond to this market with a cost effective solution. Using an all-polymer chassis was the first step toward lowering production costs. With the completion of the G36 rifle design in 1995, HK also made use of polymer fire control parts designed for that rifle, further reducing UMP cost. Finally, staying true to the simplifications made during the various MP5 improvement projects, and abandoning the expensive roller-delayed system in favor of simple blowback, enabled HK to offer it’s new UMP for $850-900 per unit in May of 1999. Comparatively, at that time a MP5/40A3 would cost a LEO $1,500 - about a 60% difference. Further, having fewer, simpler, and polymer parts, the cost of ownership of a UMP was attractive.

The transition from roller-locked sheet steel to rapid and cheap to produce poly-based gas and blowback guns was also tied to a broader downsizing and restructuring transition occurring inside HK at the time and was not unique to the UMP.

Interestingly, when viewed in a broader market context, the design process for the UMP, can be considered an abject failure. Not for the gun it delivered, but for the one it failed to deliver. While HK was focused on a SMG replacement for the MP5 (and MP5 sales remained strong in the US during this time) the military was falling in love with the M4. Federal LEOs and then local LEOs followed suite. HK completely missed the direction the market headed in during the 90s and delivered a solution – the UMP – with no problem to solve.


Utilizing a polymer construction (a material called PA6 that contains 30% glass fiber for added strength) around sections of steel inserts, the receiver is lightweight, durable and very simple to maintain. This is especially advantageous in maritime environments or circumstances requiring subpar maintenance regimens.

The UMP utilizes all-polymer (except for the spring and feed-lip reinforcements) staggered column, single-position-feed, box-type magazines that are curved in 9mm and straight in .40 and .45. Capacity is 30 rounds in 9mm and .40 and 25 rounds in .45. The UMP will accept a USC magazine, but not securely.

The UMP45 bolt weighs 11.7 ounces. All bolts contain tungsten granules that serve as an anti-bounce device. This inhibits primer ignition before bolt movement has completely stopped in the battery position.

The UMP’s cyclic rate is 600-745 rounds per minute (RPM) in .40, and 600-650 RPM in 9mm. Standard military ball .45 will deliver a cyclic rate of ~580 RPM and leave the muzzle at ~880 fps. +P .45 ammunition will increase cyclic rate to near 700 RPM and exit the barrel at ~1,250 fps (185 grain). The UMP was designed to cycle more slowly so as to enhance control – especially in .45. This also enhances burst control and allows operators to quickly learn to release double or triple shots even in the fully automatic setting.

Four different trigger packs are available for the UMP using different combinations of semi-automatic, 2-round burst, fully automatic, and safe settings. Details can be found in the UMP cut sheet located below.

The barrel is held in place by a robust steel roll pin. It can easily be removed by the operator or armorer. This allows for swapping barrels when swapping the UMP’s calibers. Once the barrel is replaced, the operator need only exchange the bolt and magazine and the caliber swap is complete. While the bolt and extractor are caliber specific, the firing pin assembly, spring and retaining pin are universal.

UMP barrels are flanged at the muzzle. This was designed for rapid mounting of muzzle devices equipped with a proprietary spring-loaded, locking-gate, quick-disconnect (QD) mechanism. Few such devices were produced. B&T produced aluminum suppressors (e.g., model SD-217831 in .45 and SD-219394 in 9mm) sold by B&T and HK. AAC and Gemtech also produced them in very limited numbers. It has been noted that when B&T designed their QD interface, they didn’t rely on factory specs for the flange and thus created a sub-par interface impeding the suppressor's full potential.

The UMP’s sights are an adjustable rear site with aperture and U-notch folding leaves and a polymer front ring with vertical post. Sight radius is 12.8 inches. It can mount four Picatinny rails: one on top of the receiver, and one on the right, left, and bottom of the handguard for attachment of accessories.

The spring-loaded bolt hold-open mechanism on the left side of the lower receiver is similar to that found on an M16/M4. It provides a manual-of-arms option in lieu of the “HK slap”.

Notable users of the UMP are the Australian Special Operations Forces (SOF), Jordanian SOF (is there any HK the Jordanians won’t buy?), Brazilian Army and Marine Corps SOF, the Latvian Army, Marine Forces of México, Romanian Army and Navy SOF, Thai Navy SEALs, U.S. Customs and Border Protection and US Pentagon Force Protection agencies. A more complete list can be found on Wikipedia’s UMP entry. Notably, the vast majority of users opted for UMP9 or UMP40. The only UMP45 users are the Georgian SOF, Malaysian Naval SOF (PASKAL), and the U.S. 5th Special Forces Group.

Here’s a video on simple function

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UMP size comparison to a MP5

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Magazine comparison of .45 and 9mm UMP magazines

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Close up of barrel flange at the UMP's muzzle

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Belgian police officer with 9mm UMP. Note the flash hider on the muzzle, forward grip/light combo and HK416 stock.

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Members of the U.S. Army's 5th Special Forces Group operating in Iraq and Afghanistan carried UMP45s as pictured above (including a close up of one in a portable gun locker).

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