Converting a H&K USC into a UMP

The H&K USC carbine is the civilian version of the H&K UMP sub machine gun. The USC has a fixed Dragunov-style stock while the UMP has a folding stock and free standing pistol grip. Apparently you can convert a USC into a UMP. Les wrote to me saying …

I recently shot a multi-gun match which required the use of a
pistol-caliber carbine and ran into two guys that were using HK UMP’s.
At first I thought they were LEO, but they said that they had just
converted HK USC’s to UMP’s by following the process below (you’ll
have to scroll)

The guys did the conversions themselves, and the pieces were high
quality, all HK part UMP clones in .45…

H&K USC into a UMP conversions

Very nice.

[ Many thanks to Les for emailing me the info. ]

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • KC

    I considered converting one a while ago, not cheap, parts kit $1500, USC is $1500 and then the cost of stamps for getting it SBR’d with a suppressor…

    nice thing though is you can use the UMP lowers (sans MG internals) and use each position (even though it’s safe-semi-semi-semi, still looks cool anyway)

  • Not all of the parts can be HK. Federal law does not allow the conversion of of imported semi-auto firearms into a non-importable configuration. By having a sufficient number of US-made parts, it is technically no longer foreign-made.

  • 18 USC 922(r):

    It shall be unlawful for any person to assemble from imported parts any semiautomatic rifle or any shotgun which is identical to any rifle or shotgun prohibited from importation under section 925 (d)(3) of this chapter as not being particularly suitable for or readily adaptable to sporting purposes except that this subsection shall not apply to—
    (1) the assembly of any such rifle or shotgun for sale or distribution by a licensed manufacturer to the United States or any department or agency thereof or to any State or any department, agency, or political subdivision thereof; or
    (2) the assembly of any such rifle or shotgun for the purposes of testing or experimentation authorized by the Attorney General.

    • Good point re: 922 .

      I guess it depends how many US-made parts they are using.

  • ap

    Wow, $1,415 for the kit! I guess I shouldn’t be surprised. I always wished they’d offer the USC in 9mm but it makes no sense, I know. Every time I start thinking of cool pistol cal carbines I end up dejected and looking at 9mm AR uppers.

  • Sam F

    I got one fully converted with 5 mags for sale… $2500!

  • Doug

    I am going through that process myself this week.
    I ordered this kit for my black USC
    It came in and all the parts dry fit.
    I will spend about 3 hours on it this weekend and let you know how it comes out.

  • John C.

    I would buy a USC, but the mags are limited to 10 rounds. you can buy 25 rounders, but they are really long because they are single stack. I might look into this converison.

  • Lance

    Very expensive though.

  • Nick

    You can buy them in various configurations including a true to UMP SBR version at the hdps website. They run about 3K.
    I want.

  • zincorium

    Steve- more accurate to say how many foreign parts remain according to the BATF’s classification, since that is what they base it off of. The US parts required will vary from gun to gun, relative to the total parts count.

  • leopard

    Magpul MIAD grip?

  • Spade

    Leopard, no way to change the grip, although I wouldn’t be shocked if at some point somebody came up with one. You can now get a metal HK lower for the 91/93/94 that takes an AR grip, although damned if i can remember who’s making it.

    HDPS offers a number of options for your US parts count. Triggers, barrels, magazine floorplates, some other stuff.
    Also, a guy on HKPro is working on 9mm bolts and barrels.

    I’ve got a USC, a UMP burst lower, and a stock sitting around waiting to be sent off to HDPS for the work. Just need the whole ‘money’ thing first.

    My USC is one of my favorite guns to shoot even with the irritating grip, so I assume the UMP will be fantastic.

  • Jon

    I bought one of the first of these a few years ago. I love it. HDPS takes care of everything. I had to search for over a year but finally found a company that made a US threaded SBR barrel that I could put on the gun. HDPS only has the HK mounted barrels and cannot seem to get true threaded barrels into production. In short, I’ve got something almost no one else has, it can be suppressed and is lots of fun! Runs like a dream!

  • Other Steve

    I missed this topic a bit. Unless you SPECIFICALLY want 45acp, and want the recoil that comes with a very light gun, I would suggest evaluating whether or not you really want a UMP – For The Cost.

    That is, the MP5 was going to be phased out because it cost too much to build. Not because it was a bad gun. Albeit a tiny bit heavy it is supposed to be for full auto use.

    The UMP was supposed to replace it but turns out there is a difference between high quality roller locked steel and a disposable blowback guns.

    The UMP is definitely a step backwards for HK. Although it does look VERY cool. If they would have hit their goal of $600-$800 I would be all over it! But at $3,000+ you’ve got to out of your damn mind.

  • Matt Gregg

    I think I’d much rather save the cash and buy a CX4 storm if I wanted a .45 ACP carbine. Or even a mech tech conversion for a glock 21.