H&K Ump45 Review

The Ump hasn’t been given a lot of love here so hopefully, I can help somebody out.

Firstly a little bit of background. The casing isn’t made by the same toy companies and isn’t paired with a gearbox from the factory. A lot of the Gelsoft companies in AU will import the cases and pair it with a JinMing Gen 8 gearbox as well as aluminum barrel and sell it as a package. This means that the quality of this build seems to be comparably higher than other Gelsoft ■■■■, especially those who are made from plastic.

I bought mine from Tactical Edge, the customer service was pretty good and would have been even better if they weren’t extremely busy. The guy let I spoke to me try a bunch of different ■■■■ and when I was ready to buy, he took it out of the box, made sure everything was good to go and threw in a free 2000mah 7.4v 25C battery which seems to be plenty for a gel blaster.

Onto the gearbox, it’s a standard JM Gen 8 box, 460 motor (33000rpm), plastic gears, plunger, and everything else. That being said all of the gears in my box came perfectly aligned (no need for shimming:). Something not so perfect is the plunger and o-ring. Holding your finger over the front of the nozel, you should be able to feel the compression when you push the plunger in. Mine has none. Zero. The o-ring does nothing for compression, nor does it create a seal and as a result, I can only accurately shoot about 20m. The first 10 is extremely accurate (probably because of the barrel) and then it’s up to whichever star you wish on after that. The rate of fire seems to be a little above average but nothing to write home about. I’ve got a nylon box and 1.4 spring coming so I’ll follow this up with the install.

The aluminum barrel flexes a little under fire but the included barrel stabiliser does a pretty good job at eliminating most if not all of it. I believe it’s standard threading so it’s pretty much open season.

Speaking of open season, the battery compartment is far from it. It’s small, square and extremely inconvenient. It measures in at approx. 24mmx24mm and will only really fit the chinese batteries that you see all over ebay and aliexpress. Even then I’d really only recommend the the smaller square ones because you’ll run into a cocking issue with the cylindrical ones: You won’t be able to cock the ■■■ all the way back as the battery interferes with the sliding mechanism. This won’t matter if you’re not planning a mag prime mod but it’s something working thinking about.

It’s also worth noting it came with little red thing to put on the end of the barrel (meaning it’s not a real weapon) but it’s a pretty big eye sore and the barrel is already a pretty cool red. It also came with a packet (probably 10,000) blue balls I’ll probably test them one day when I’m running low on milky gels.

I think that covers everything, if there’s anything I’ve missed ask below. I’ll follow this up with magazine capacity tomorrow. Stay tuned for a full teardown and future mods.



Appreciate the review and breakdown pics @RoyceJ. Actually looking into this shell for a dsg build as I wanted something different to the m4 style - but still wanted the top/bottom split receiver style however I note that the bottom half splits into lh/rh. Are you able to confirm if you can remove the gb without splitting the bottom half?


The blue gel balls aren’t the best, they have a tendancy to explode as they are fired.

The gearbox sits in notches in the nylon housing. You need to split the lower half to remove the gearbox.

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