Do you have to do anything on the USC receiver with a stock block?

You have to mill out the mag well to be wide enough to accept the UMP mags. Most people also mill the vent holes in the handguards but that's obviously not required.

Thanks!

It has arrived.

Congrats!

Price?

$1285

I just got mine last night. I got two mags, a manual and that was it. Did any of yours come with a Picatinny top rail? HK Parts sells two different sets, but still. Very strange.

The dealer got the rifle directly from HK. The box it came in was really beat up, and the gun was wrapped with a foam pad along with the mags and manual. The dealer showed me the box and the address (it was from HK not a distributor). Very weird. My Zenith Z5 rifle came with a nice case and all the trimmings. I would have at least expected them to include Picatinny rails and ship it in a nice new cardboard box (like when you open a Benelli shotgun).

I’m going to try to shoot it this week and decide what I want to do with it (keep as is or convert to UMP). I already wish the angle of the pistol grip was more upright (like a BCM pistol grip on an AR). The safety is very easy to manipulate though.

So what are the stock options for these things,  is there anything available that does not require sending the rifle out for a conversion?   Seems like the MPX/Scorpion/B&T'S/ect... all had a multitude of stock options open release.

No rails come with the carbine. HDPS makes a nice set.

As far as I’m aware, you have to convert it. If HK did what Zenith or B&T was doing, this would not be an issue and we would have functional UMPs. I don’t understand why they just have them assembled here in the US.

So I shot the USC. Overall it’s OK. It’s not the panacea people make it out to be. Here our my thoughts:

1. The pistol grip needs to be more vertical. It is way too angled for my tastes

2. I cannot believe H&K is forcing me to use a 5 mm allen wrench to take off the stock. That alone will prompt me to convert the darn thing.

3. The fore arm is nice and I like the hand stop

4. Not sure why they put a hood over the front sight for a gun like this. Not sure if cutting out 1/3 of it is even feasible give the polymer construction. It will make using a red dot more difficult.

5. Recoil is noticeably greater than my Zenith MP5 clone and AR in 9 mm. Just as smokey as well . Regardless, it is manageable once you get used to how the gun cycles.

6. The trigger was perfectly fine. I did have a few instances though where the bolt release would not launch the carrier forward (had to use the cocking handle). May need break in, but the gun ran flawlessly.

I may go ahead and convert the thing and get the barrel threaded. Not sure if I’ll SBR it our not.

About the 5 mm allen wrench remark, I was complaining about the lack of push pins like any other HK gun. I’m sure it all has to do with German export regs or how they had to get it BATF approved......of course, they still give us the MR556/762 with captive push pins.

and yes I realize there will be more smoke and recoil. It wasn’t as bad as I thought

U need to do the ump conversion. Makes the gun immensely enjoyable even if u keave the 16in barrel. As a sbr its amazing. Buy a ump fbi semi lower, buy a stock block b for use with the ump factory stock. Do a little milling and voila, fun times. I did everything with a dremel in five minutes.  The thumbhole grip sucks and so does the 10 rounder. The factory 25 round mag is awesome but u should get a loader.

Ive been looking for one locally. No one will order it either. Assholes.

Finding them used, for prices all over the place. Found one on Armslist, but a few states away. Dont feel comfy doing long distance deals there. Only Local guys are trying to sell converted setups for outrageous prices. May have missed the ball.

Guess I will hound the EE and other forums for those who get discouraged from the prices of the conversions.

Tom Bostic sent me this pic from my conversion. Should be delivered today.

I work for a H&K distributor.  I don't think there will be many of these.

That's beautiful. Post more pictures when you get it.

So for a USC + conversion to a UMP, what is the all in cost. Something like ~mid $2000s all in?

I'm in for $2650 with the fuse job. That's without mags and rails. A stock block conversion would have been about $400 cheaper. I'll still need to get the barrel chopped and threaded when my form 1 comes back.

Instead of chopping the barrel you can buy a new US made barrel.  They are easy to swap.

Not worth the extra expense since I'll never need to put the long barrel back in. I'm cutting it shorter than factory UMP length so my Silencerco 3 lug will be closer to the forend. Considered the flanged barrel, but the cans aren't the easiest to find and have limited use so the Hybrid will have to do.

I have mine at Tom Bostic’s now. I’ll post a range report in the next week or two.

I went with the stock block B conversion. I don’t like the idea of fused plastic. I want to use this at PCC matches.

I don't think the stock block is a bad choice. I just like the easier takedown and look of the fuse job. I can't even tell where it was done. I may get a second one and do a block conversion in 9mm. I did find out the US sear is a waste and doesn't work with the US trigger.

Attached File


Tommy just emailed me this pic. Looks awesome. I had him cut off the top of the front sight hood for me as well. I did just about everything minus the “UMP” markings. I may SBR this at some point, but for now, I’ll shoot the heck out of it.

I’ll post a full report when I take it to the range in the next week or two.

Sweet.

So I took it out alongside my other two PCCs yesterday to compare all three:

Attached File


Zenith Z5 rifle, USC converted to a UMP 45, and my CMMG Mk9T (takes Colt mags).

1. Zenith: Runs without hiccups. I tried a Spuhr AR stock adaptor, and I honeslty don’t think it give me much more control of recoil. I actually don’t like the fact the red dot sight sits much higher than it would otherwise with the Spuhr set up. I prefer the standard A2 stock. My problem now with this rifle is I’ve tried Zenith’s rail and a Spuhr rail. They don’t mate up to the receiver in line (level) with the iron sights. I will be calling Zenith this week about it. I already had them fix the front push pin hole so it would line up with their lower and a FBI lower better. Regardless, if I get the optics rail thing resolved, I could easily see myself running this in a PCC match with an Aimpoint on top. It has not had a single hiccup on me shooting mostly 124 grain NATO ammo.

2. USC to UMP converted by Tom Bostic: I love this gun. It is a total very accurate tack driver. It put a grin on my face while shooting it. I found it to have less gas in my face than the Zenith or CMMG. I wish B&T made a collapsible/folding stock for the UMP, but the folding stock with the stock block conversion is not that bad. This is going to be my go to PCC, assuming I can find some mag carriers for it (I have a light weight BFG chest rig that works, but not sure if that is PCC match legal). The recoil is not at all bad; I find it very controlable shooting semi auto as you use appropriate technique. Sure, it’s not as fast as 9 mm, but I love shooting .45 ACP. I am thinking about turning this into a SBR and buying an AAC Tirant can for this rifle. The only malfunction I had with it was when I used a 100% US made mag from HK parts. It was a single FTF, and I think it may have been due to a bad round. The German mags with a US made follower and floor plate worked fine. My gun ate Winchest PDX1s and Federal HST 230 grain JHP loads without any diffuclty. I may get a US made bolt carrier to give me another US made part in addition to Tom Bostic’s trigger which I already have installed. Regardless, I’m going to buy another USC and convert it to a UMP 9. I may sell the Zenith pending the resolution of the optics rail.

3. CMMG Mk9T: I’ve had this gun a for a year now. I just installed a PRI 9 mm gas buster charging handle on it, and it does help deflect more gas away from the face. However, it runs great. Never had any problems with the rifle shooting 124 grain NATO loads (usually MEN or Prvi). Obviously, with the 11” handguard, I have no issues with control (I like long handguards because I have long arms). The ergonomics are the best of the three (UMP is honestly pretty close once you get used to it). My only issue is the gas to the face, and I know it gets far worse if I were to suppress it. I bought this right before the CMMG Guard came out, so yes, I am kicking myself. I also have a Defcan 9 inbound. I’m thinking about selling it to fund the UMP9, but I hate to part with a functioning rifle that runs well

Regardless, if you are on the fence about convering a USC to a UMP, I encourage you to do it. If you like shooting PCCs, a UMP 45 conversion is a lot of fun. Downside is that it is very expensive ($1500 for USC + $1000 for a stock block conversion with the required parts).