HK UMP Submachinegun and USC Rifle

The HK UMP submachinegun is a low cost weapon sold by HK on the world market as a general purpose law enforcement and security weapon.   While not readily available for domestic sales to the general public in the US, these guns are likely to become more common on the world market in addition to the likely re-release of a semi-auto version originally billed as the HK USC.   The primary differences between the USC and UMP being that the UMP has a shorter barrel, ability to add a sound suppressor, selective fire (semi and full auto, but no three shot burst), a folding stock, and a “high capacity” 25 shot magazine.   The appeal of both weapons to law enforcement and security personnel is that they are simple to operate, powerful at short ranges, and capable of withstanding hard environments.   This has been an important and valid selling point for maritime security personnel who leave their weapons on ships and boats with exposure to salt spray and fog most of the time.    It is also rumored that these guns are becoming more common for use in and around airports and with private aviation security personnel.   In those environments, the increased penetration of the 9mm can be more of a problem than it is worth.   The .45 ACP cartridge most common to the UMP (although other variants do come in .40 and 9mm) loses velocity at longer ranges and poses less of a risk to innocent bystanders or sensitive equipment in shooting situations.

Operation is from the closed bolt in both the semi-and the full auto guns.  The magazines are single position feed magazines, although the “civilian” version normally is a narrower single stack magazine while the subgun gets a double stack mag that is actually quite bulky for its capacity.   An aftermarket company makes a magwell conversion for these guns so that they can use the steel M3 Greasegun mags that have been used in several post WW2 submachinegun designs including most MACs and a number of guns developed for use in third world nations during the Cold War.   These single position feed magazines are much more difficult to load than the MP-5 standard magazines and there is no compatible “rapid loader” on the market for UMP mags.

Accuracy is tolerable with these weapons and nothing to brag about or be ashamed of.   The semi-auto “civilian” version with its longer barrel will squeeze a bit more velocity and accuracy out of the .45 cartridge and make the gun effective out to 100 yards.   Realistic range of the subgun is more like 50.

Standard sights are a polymer fixed ghost ring arrangement that is sufficient for use with no modification, but serious users will want to install some sort of optic in order to get the best performance out of the UMP as a weapon system.    Another extremely important add-on (in my opinion) is a vertical foregrip.   Beyond that, some improved sling mounts and a flashlight would round out the package quite well.   The accessories are to be installed using HK’s clever Picatinny accessory rail system that bolts onto the plastic surfaces of the gun to be held in by nuts that were set in the skeleton frame of the gun before the polymers were molded around the skeleton.   Unfortunately, my sample gun did not have these added features which you can see in this stock photo from one of the HK websites.   Like most subguns, this gun would perform a whole lot better with some sort of red dot or reflex sight.

The selectors are fully ambidextrous and the cocking handle fairly easy to reach with either hand.   The bolt stop/release seems difficult to reach with either hand and I found myself just using the cocking handle to disengage the bolt catch once I have seated a new mag.   The magazine release is small and does not lend itself to super fast mag changes, but training and practice can overcome most of that problem.   The stock mechanism on the folding stock models folds easy and locks open very rigid.   They have also done a good job of integrating the folding stock design into the rest of the gun instead of making it an afterthought.

Magazines for these guns are big, especially considering the not-so impressive capacity of the mags.  10 shots in the semiauto rifle and 25 in the subgun.    The thing is, you also have to consider that each bullet fired from this gun is exactly twice as big as the average lightweight 9mm bullet.   IE, 230 grains of .45 Ball is twice as much as 115 grains of 9mm.    The cartridges are fat, so a double feed magazine would require a larger gun according to HK engineers (funny, old Col Thompson did not think so).    This HK magazine is actually quite similar in overall dimension to the old M3 Grease gun magazines and  you do have one small US company making a conversion kit for the USC carbine that will allow it to use the M3 “grease gun” magazines which are considerably cheaper than the HK mags which are actually a pretty complex thing to make, albeit simple when they are finished.   The HK mags are actually a steel skeleton with plastic molded around it, then a clear plastic window bedded into the side.   The USC mags are single stack, so they are actually about as long as the UMP mags, but slimmer.   In either event, it can be tricky to find mag pouches anywhere that will fit these mags.   More so with the high capacity variants because they really are big, as you can see in this picture when compared to magazines from an MP-5 which hold 30 rounds.

If you are familiar with the M16/AR15 type guns and the older HK designs like the MP-5, HK-91 and CETME, you don’t have much to learn when it comes to handling the UMP.   It basically works like an MP-5 but with a bolt stop like an M16.   Sights are basic, but the sight picture is not significantly different from the older HK rifles.    The grip and cheek weld, however, seem more influenced by the M16.   This makes sense for a gun that was developed primarily for the US market where many, if not most, law enforcement tactical personnel have prior US military training.    Ergonomics on the gun are a fair mix of Mp5 and M16.

The feel of the gun is unique in that it feels oversized and lightweight.  The USC in particular is quite flexible and a reasonably strong person can grab the front and rear of the gun and flex the whole thing three to five degrees one way or the other.   I also found that it is not difficult to shift a mounted Eotech a couple degrees to either side although it would quickly spring back to its original position.   This apparently does not adversely affect the accuracy of the gun since the core of it is a steel skeleton and free floated barrel that is thicker than most other .45 rifle and subgun barrels.    You also get some added rigidity and stability when adding accessories like the bolt on metal outer rails.   The gun has a very noticeable recoil with heavier loads and the vertical foregrip is all but necessary to control the gun in rapid fire.

In shooting the USC with the factory ten shot mags, it does not seem as crippled by the short magazine capacity as similar 9mm rifles would be.  A part of this is the light weight and moderate recoil of the gun requires a shot to shot recovery time that slows down the practical speed at which you can empty the magazine.    Thus, just as a lot of people don’t feel shortchanged if a 20g home defense shotgun  runs out of ammo at nine shots, the USC does not seem entirely lame when used with the ten shot magazines.   It is also easy to see how the potent .45 ACP when fired out of a carbine length barrel is usually going to be a “one shot stopper” in most short range engagements.    One caveat of this cartridge however is the pronounced trajectory, even with a barrel that is considerably longer than what you get with .45 handguns.   Your aiming point at 15 yards is going to need to be considerably different from your aiming point at 75 yards.   The gun is usable out to 20 yards, but at that point, the aiming point will quite possibly be out of the adjustment capabilities of most optical sights.

The bulk of the gun gives me the impression like one would have as a child playing with an oversized toy gun.   This is definitely not familiar ground for those who are accustomed to compact but heavy subguns like the Uzi.    It also severely limits the concealability of the gun even when folded.   The USC carbine is dimensionally the same through the action, but of course larger up front due to the long barrel.   The long barrel of the USC is not necessarily a bad thing since it does a lot to flatten out the trajectory of the otherwise slow moving .45 ACP round at longer distances.    Still, the USC with an optic and ten shot magazine is a very bulky weapon that becomes quite ungainly in close quarters.    It has been billed by some gun writers and security consultants as a good weapon for civilian boat owners traveling longer distances with some chances of running into modern pirates but needing a weapon that had (at the time) not been classified as an assault weapon as most pistol caliber carbines end up.   The problem with that role for the USC is that it is simply too bulky to employ effectively within the confines of the average sailboat boat below deck.    With that in mind now that the ban is over, a folding stock conversion and chopping a few inches off the barrel would make the gun more suitable for the boat defense role, but then so would any one of several decent .45 pistols at a fraction of the cost.

The USC was dropped from production and importation for the US market in 2002 and thus even with the 94 to 04 assault weapon ban expiration, prices of the USC have been rising.    Oddly enough, the gun was dropped from import not because of legal pressure, but because they were poor performers on the market.   The main perception among gun aficionados being that HK was trying to “get over” on the gun nuts by marketing a rifle that was mainly show and not much go.   Strip away the “as used by the special operations community” mystique and what you end up with is an oversized ten shot plastic rifle for an obscenely high cost to performance ratio.   The lines of the weapon are quite stylish, and the thumbhole stock while looking pretty good, incorporates an oversized pistol grip that makes it difficult to reach the safety.   Accuracy on the gun, however, is quite good due to the high quality free floated heavy barrel that is built into every version.   I personally think the optimum barrel length for this weapon platform is around 12″ which is part way between the length of the standard USC and UMP barrels.    The story, however is not quite over and the nails are not quite in the coffin for the USC yet.   What has been its saving grace of late has been the innovations of a few die hard fans of HK product working separately but toward the same goal of making the USC a more suitable weapon.

First, someone at HK decided to retain their brain and make the USC compatible with most of the UMP accessories.  The magazine situation between the two guns is hopelessly convoluted, with the USC taking an entirely different magazine than the UMP, and the UMP taking a fairly costly and oversized 25 shot magazine of their own design.    Both are single position feed mags similar to what was popular in older subguns.   This brought on the innovation from a guy in Arizona to come up with a conversion unit that would allow the USC to use much cheaper and readily available M3 Grease gun magazines that had been in production from WW2 to the 1980s with the bulk of them made from 1943 to 1960 and used in vast numbers by the US government and its allies.    The cheap and ready availability of such magazines over the years has made them a number one choice for workshop weapon designers like Charles Ingram and Mitch WerBell who incorporated them into their MAC-10 subguns.   In addition, a number of grease gun compatible Thompson clones had been marketed from the 1960s to the 1990s.    In addition to the USC being compatible wiht UMP accessories, private interests in the US, namely Top Notch out of Arizona, have come up with a conversion package that replaces most of the lower half of the USC in order to make it more similar to the UMP.   This includes replacement of the stock and lower receiver and that lower receiver conversion will accept cheap and readily available M3 magazines instead of the original HK mags.   The result is the potential for the otherwise dismal USC to become a rather attractive package with some real merits as a functional weapon.

more to come later


Cost – Priced lower than other HK subguns and carbines, the UMP/USC guns are still more costly than a lot of worthy weapons. Accessories – These guns were engineered to be used with standard Picatinny accessory rails which are optional, but should have been included with every gun of this type.   The rails make the gun compatible with a vast number of industry standard ad-ons.
Mags – Costly and difficult to obtain.   Conversion kits are available to allow the USC carbine to take M3 Grease gun mags, but even those WW2 and Korea era mags are starting to become uncommon.   Magazines are a weak link in this system and will wear out with extended use because they are single position feed mags made primarily of plastic. Longevity and durability – These guns are built primarily of polymers and it is unlikely they will last for decades like similar steel and wood guns will last.   These were engineered for use by government agencies which replace weapons on a fairly regular basis.   Early models of the UMP subgun suffered from stress faliures when used with high impulse .45 ammo which drives home the point that these are designed as short lived guns.   The light weight and robust plastics of the guns does make them suitable for high stress short term use.  In either event, these are not heirloom grade guns.
Ammunition – Easy to obtain and readily available in most of North America.   The design of the gun is tolerant of most hardball .45 auto ammo but hollowpoints can sometimes be problematic. Power – The guns come in .45 auto but there has been some limited distribution of 9mm and .40 version of the UMP to the law enforcement market.   The power of this gun is consistent with similar service handguns and I noticed no particular increase in power of the .45 rifle over that of the .45 pistol which is unlike the situation with 9mm rifles and pistols where 9mm rifles firing full power NATO ammo are usually considerably more powerful than 9mm pistols due to the fact that the longer barrels build significantly more velocity.
Parts –  Spare parts for the guns are extremely difficult to obtain if you are not a government agency.   If you cannot fabricate parts, you may have to consider this a throwaway gun. Ergonomics and handling – Different but decent.  The guns handle like an M16 combined with an MP-5, two weapons that most US military and law enforcement trained people are usually familiar with.   The grip on the semiauto carbine is too big to allow efficient manipulation of the safety lever.   It is my opinion that the butt stocks on these guns are simply too long.
Popularity – Engineered to be the pistol caliber carbines of choice for budget minded law enforcement and security operations, the UMP and USC have suffered a lack of popularity on the market although the UMPs remain readily available.    USCs have been withdrawn from the US market and are not very highly prized by HK collectors. Maintenance and repair – Parte are extremely difficult to obtain for these guns but they are mechanically fairly simple and I think it would not be incredibly difficult to fabricate some of the parts if it became necessary.   The mechanics of the guns are dirt simple and easy to figure out.
Accuracy – The guns are not realistically usable beyond 100 meters and are at their best under 50 meters.  While the inherent accuracy of the guns is good, they are limited by the fact that the .45 auto cartridge is a short range cartridge with a pronounced trajectory. Reliability – The guns I have tested were 99% reliable.  Failures to feed seemed to be related to the single position feed magazines.   Lubricating the mags and being careful to clean powder residue out from around the feed lips helped eliminate the problem.



Larry Pearson is an NRA certified pistol instructor and a member of the American Society of Law Enforcement Trainers, as well as a former police officer, former military firearms instructor and lifelong student of the martial arts. He also felt that he had something of value to share with the firearms community, and wondered which gunzines he should approach with the above essay. The problem was that he was dealing in ideas and concepts, and virtually all of the present gunzines only want articles about products and services so that their advertising department can sell space and everyone can make money. This is the American way. This is his first published work.

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