The Evolution of The H&K .45 ACP Handgun

Heckler and Koch has had something of a spotty history with the American .45 ACP caliber. Originally, H&K -typically for a European company – was dismissive of the caliber, and felt they could not make a business case for weapons chambered in it. .45 ACP is after all, only really popular in the US and Southeast Asia. At the same time, H&K had a very close relationship with some US special units and law enforcement agencies that naturally desired weapons in that common caliber. Eventually, the dam broke and in H&K fully embraced the .45 ACP caliber with weapons like the UMP and their ever-changing polymer pistol line. Christopher Bartocci, writing for SADJ, has outlined the H&K .45 ACP pistol evolution:

Traditionally, Heckler & Koch has been known for making some of the finest pistols and assault rifles in the industry. They have also had a major handicap that has prevented them from being as prevalent in the law enforcement and military market: the extremely higher than normal price. H&K has priced themselves out of much of the commercial and military market in the U.S. In 1989, H&K completed a study of the United States pistol market and came up with a set of criteria they would need to meet to compete with Glock, Beretta, SIG Sauer and Smith & Wesson. In September of 1989 work began on this new generation pistol. The criteria needed for this new pistol was to be affordably priced, conventional design, innovative features, reliable, durable, safe, accurate, high quality, advanced materials, large magazine capacity, low recoil, user friendly, many modes of operation and conventional locking system.

During these early days of research and development, another pistol opportunity presented itself. In February of 1991, United States Special Operations Command announced their Offensive Handgun Weapon System (OHWS) proposal. Much of the criteria for both pistols were the same and both pistols would use the same basic technology. The OHWS would be put through the toughest testing the world has ever seen for a pistol. In September 1991 the acronym USP or Universal Self-loading Pistol was assigned to the new family of weapons. The pistol was designed for the newly introduced .40 S&W caliber pistol. Unlike most of the other pistols in the industry, the USP was designed for this new caliber, not a 9mm pistol modified for the larger caliber. Prototype 1 was reviewed in February 1992 and the second prototype in June of 1992. In August of 1992, H&K delivered 30 OHWS pistols to SOCOM, which would eventually be adopted as the MK23 MOD O pistol. In September of 1992, the third prototype was reviewed and endurance testing began. In December, both the USP40 and USP9 completed the first half of the 20,000 round endurance testing. Upon completion, the USP design was frozen and production planning began. The USP was unveiled at SHOT Show in 1993 and in February 1993 USP production began at H&K GmbH in Germany. That same month the USP40 Variant 7 was submitted to U.S. INS/Border Patrol for evaluation. In April of 1993 the first USP40s arrived for sale at H&K Inc. for purchase, followed in June by the USP9.

Although the USP is 20 years old, it is still state-of-the-art. H&K continues to build on it modernizing it for the changing times. The USP series pistol is in service throughout the world, although not necessarily in .45 Auto caliber. There is no doubt that the .45 Auto is America’s caliber and will be with us for a very long time. Deep rooted in tradition as well as a well backed up reputation make it one of the finest combat pistol calibers of all time. H&K has undoubtedly been on the forefront of modernizing pistols to fire this over 100 year old cartridge with the MK23, making the most advanced handgun in the world using this proven cartridge. The American market will continue to procure pistols from H&K in this caliber and by Americans I mean commercial, law enforcement as well as military. These pistols have seen service with American forces in the Global War on Terrorism as well as many other places throughout the globe including the MK23, USP45 and the USP45 Tactical models. The adaptability to any trigger variation has also put this gun on the list for law enforcement. Although not the most popular caliber abroad, the pistols in their 9mm variations are in use by the security forces of Australia, Denmark, Estonia, France, Germany, Greece, Ireland, Japan, Lithuania, Luxembourg, Malaysia, Poland, Portugal, Singapore, South Africa and Spain. Also in that lineup are numerous U.S. military and law enforcement agencies.

When visiting Alex C’s machine gun palace, I got to take a look at the Mark 23 handgun. Of all the pistols he had, that one made by far the biggest impression on me. Its comical size is endearing in a way that’s totally unique to me (granted, I have not yet seen a Mars pistol in person). Pictures simply cannot convey how huge and cartoonish the Mark 23 is; I found myself constantly picking it up, contemplating its gigantic size, and bursting into laughter.

The USP, and its offspring the HK45 have really set the bar high for modern handguns, as well. While I feel for budget and practical considerations the Glock 19 is still the standard handgun I would recommend to a new buyer, in terms of quality the H&K line of wunderplastic pistols is very hard to beat indeed.

Nathaniel F

Nathaniel is a history enthusiast and firearms hobbyist whose primary interest lies in military small arms technological developments beginning with the smokeless powder era. In addition to contributing to The Firearm Blog, he runs 196,800 Revolutions Per Minute, a blog devoted to modern small arms design and theory. He is also the author of the original web serial Heartblood, which is being updated and edited regularly. He can be reached via email at


  • G0rdon_Fr33man

    The size of the Mark 23 is somewhat of an optical illusion. It has the bigger trigger guard and a massive slide, and it makes it look like a standard 5-inch pistol for giants, but the grip are only a tad bigger then standard USP. It is also a magnificent shooter.

    Is it true they are no longer made?

    • hami

      The rumor has been that they will stop(or have stopped) production. My Mark 23 has a 2013 date code so if they did finally stop it wasn’t too long ago.

      • mugwump

        I also have a 2013, but here in Canada I’ve seen a 2014 for sale with correct date code. Our HK’s come direct from Germany if I not mistaken so maybe HK USA Had a surplus of 2013’s?

    • Vitsaus

      Its not an optical illusion, its massive. The grip is right in the neighborhood of a Desert Eagle, which is also massive.

      • G0rdon_Fr33man

        No it is not. I own a Mark 23 and a Desert Eagle. The Mark 23´s grip is close to that of an USP .45 tactical. The size of the upper is comparable to the D.E in size, but not weight.

    • Alex(not C.)

      They do still make it, but not very many. I’m pretty sure they never really cranked them out to begin with, and after developing so many new pistols they make fewer and fewer a year. It’s still on their website, though. Mine’s a 2013 and the S/N is only 16XXX

      • Mmmtacos

        That is quite interesting. For some perspective, your 2013 Mark 23 is S/N 16XXX and my VP9 I acquired in September 2014 is S/N 17XXX. If they both started at 00001 then good on the VP9 and good for H&K.

        I still want a Mark 23, but even at the better-than-it-was-before price of $1,800 NIB I just can’t justify it. I’d sell off my USP 45 to help with it, but even privately I’d be lucky to get as much as $700 (which, at least, is what I paid for it myself).

    • DonDrapersAcidTrip

      Full size USPs always looked like giant ass robocop guns to my hands anyway though

      • G0rdon_Fr33man

        Childrens hands 🙂

        • DonDrapersAcidTrip

          uh do you always creepily smile at the thought of childrens hands

  • Günter Groß

    This reads just as the USP was H&K’s first pistol in .45 ACP. Which is not true. The Model P9S in .45ACP was built since 1976. One of the most precise pistols.

  • Lol @ machine gun palace! You’re welcome anytime my friend. He is not kidding when he says that he picked up the Mark 23 and laughed on numerous occasions. It drew him like a magnet, ha ha.
    But if the readers would like I can do a TFBTV segment on various Hechler and Koch handguns. Maybe start with the HK4 and work up to modernity?

  • Green Hell

    Basicly this picture says it all. Even holding a an airsoft Mark 23 you could notice that it feels even bigger than Desert Eagle in your hands. It looks like HK really had a lot of irrational fears approaching the creation of their first polymer framed .45 ACP “hand cannon”.

    • john huscio

      goliath’s CCW

  • CommonSense23

    Fortunately Socom has finally got around to replacing the 23s with the 24s

    • They haven’t really. They still have and use lots of MK23s. My friend was attached to a special forces unit and they had a bunch. Here he is a few years back with one over in the sandbox:

      • CommonSense23

        They are filtering them out pretty quickly at this point. It’s a item that is being replaced on a one for one basis. And SF has a ton of people to support. They take a while to replace their stocks.

  • Lance

    H&Ks prices make me goto other names if your in the market for a pistol Glock, S&W, and Beretta are alot cheaper than even a basic H&K. USP is a good gun the tactical model should have been the SOCOM winner since its reduced size and weight would made made it more popular and may have been used outside of the SEALs in SOCOM.

    • Anomanom

      I have to agree, while i have the standard model, rather than the tactical, my USP45 is as spot on as a pistol can be IMO. Accurate, easy to use, good capacity (up to 20 rounds), and unlike most polymer guns, it has a manual safety/decocker for those that like it traditional.

    • CommonSense23

      You know the HK45C is already in use with Socom right.

  • “Alex C’s machine gun palace.”

    Here I am imagining him as a grand mogul of Class III guns, sitting atop his throne of NFA items and pre-ban M855, with a rotund belly, a barytone voice, and nubile servants, living in a literal machine gun palace where they cover the walls. And behind his gun throne, a huge painting of him, dual-wielding M60s but with an almost Buddha-like smile.

    Maybe my imagination is way too vivid.

    • Don Ward

      Between the time when the oceans drank Atlantis and the rise of the sons of Aryas, there was an age undreamed of. And unto this, Alex C(onan), destined to wear the jeweled crown of Aquilonia upon a troubled brow. It is I, his chronicler, who alone can tell thee of his saga. Let me tell you of the days of high adventure!

  • Jon Baker

    Now if only they’d make a VP-45, preferably with ~12 round magazines… I mean, I like my HK45, and I love my VP-9, so taking the caliber, barrel, and frame size of the .45 while incorporating the interchangeable backstrap AND side panels, as well as the great trigger, of the VP-9, plus ditching the ludicrously oversized for capacity HK45 mags for a better design, would pretty much be my ideal duty handgun. I imagine more than a few military and police users would be interested as well, especially if they managed to keep it around the price point of the VP-9.

  • petru sova

    Just remember the H&K pistols are now using MIM cast parts and we all know how unreliable those parts are.

  • petru sova

    On the other side of the coin Seecamp refuses to use MIM cast parts because he the owner believes in making a reliable pistol whose parts do not fail at the critical moment. Think about it, what would be better to have in your hand a .32 Seecamp or a 9mm Seecamp that you know will work or an HK with MIM cast parts in 45 acp that might or might not work.
    If you want a reliable .45 use a Detonics they too refuse to use MIM cast parts.