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Discussion Starter · #1 ·
And so it begins: 9mm USC to 16" UMP Conversion and links to ALL UMP Conversion Info!

Well I *think* I’m the first person to undertake this particular conversion although I believe others have already done the 9mm UMP conversion with the 8” Barrel (feel free to chime in here guys! :)).

My main purpose here is to actually create a place with ALL the links and other information needed to complete a DIY USC to UMP conversion of any caliber.

First let me say this article is in NO way to say that you should not use any of the vendors that offer this conversion, rather than simply a place to find links and other pertinent info for those of us who really enjoy cutting up a brand new gun :D

Links to Machining Information for Conversion:
A VERY Basic Guide, read this first to get an idea of what needs to be done:
http://tradecraft.us/Firearms/HowToUMP/HowToUMP.htm

A VERY DETAILED Guide, read this when you have your parts and are ready for specs!
http://home.comcast.net/~UMPlower/

UMP Foregrip Vent Location:
http://myweb.cableone.net/jsheffi31/Slots.htm

UMP Mag Well Template
http://hkpro.com/forum/attachment.php?attachmentid=1743&stc=1&d=1188954110

UMP/USC Parts Comparisons (See Gallery)
www.tacticalexcellence.com

NFA Information that may be helpful when doing conversions:
http://www.top-notchparts.com/atf_nfa_letters.htm

Links to Suppliers for Conversion Parts (The ones I personally used)
Adam Webber HK4Evr www.hkparts.net
Ed HDPS www.hdps.org
Top Notch Parts www.top-notchparts.com
Other Suppliers of Note:
Gordon Miller - www.hkspecialist.net
Phil Flack - [email protected]
Clyde Armory - www.policeguns.com

Now that I’ve got the basics out of the way I’m going to document what’s needed to do this conversion AND change calibers. I couldn’t find a lot of the information I needed easily such as how much I needed to change the bolt, 16” barrel suppliers ect. Let me start off by saying that while the regular 45ACP UMP conversion is actually very reasonable if you buy parts from the suppliers listed above, changing calibers can be VERY EXPENSIVE; you have been warned :D

Caliber Specific Conversion Parts:
Bolt Assembly
Barrell
Magazines

I bought all of the above parts (and parts for all my other guns) from Adam Webber (www.hkparts.net) and I can’t say enough about him and his service; amazing! Now before you go and call/email/homing pigeon ect Adam, he doesn’t have any more 9mm parts but does have plenty of 45 and I believe even some 40 parts. I will warn you that in my experience the 9mm parts may as well be made from un-obtainium as I had a HELL of a time finding ANYTHING in 9mm.

By now you are asking "Why the hell would he want 9mm?" Well the answer is relatively simple; I like 9mm :) All of my other guns (with the exception of the AR) are 9mm.

I was able to find ONE supplier that made a handful of 16” .40/9mm barrels and that was Top Notch. According to the gentleman I spoke to when I ordered he believed I was the first to buy one of the 16” units but still had a few left. I also bought an 8” HK barrel from Adam on the odd chance that someday Michigan will allow SBR (HA!).

The Parts:
HK 8” UMP 9mm Barrel, 9mm Magazine, 9mm Bolt Group (.45/.40/9mm all use the same recoil rod BTW) and some extra barrel pins.



Now that I’ve got these parts I’ll start to document what you need to do to the bolt to assemble this thing as well as updating this when my 16” Barrel arrives and how the gunfunctions/looks ect. I hope this post will help some people not have to search for hours to find information like I did!
 

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Very cool...

Do you want this to be all encompassing for the USC to UMP conversion?

Here are a couple other part suppliers to add to the list of good guys to deal with:

Gordon Miller - www.hkspecialist.net
Phil Flack - [email protected]
Clyde Armory - www.policeguns.com

I also had Jeff Smith at Tactical Excellence modify my .40 SW bolt to work in my UMP. His site is worth referencing for a comparison of the USC, UMP9 UMP40, and UMP45 bolts. He also has some great pictures of the older and newer UMP lower differences.

BF
 

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Now that I’ve got these parts
I hate you. I want a 9mm UMP :(

I'd even settle for an MP5 style 9mm clone.

On a side note, the AG has put together a two panels of experts (term used VERY loosely), one to report all the positive aspects of allowing suppressors and SBR's in Michigan. Then also a panel to report what negative affects it would have.

When they finish, years from now, he will use that to help make is decision.

Personally, I can't think of too much negative. It's just a waiting game now.
 

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Discussion Starter · #4 ·
Ah your right I almost forgot about the Tactical Excellence site! I'm going to add those right now; thanks!
 

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Discussion Starter · #5 ·
I hate you. I want a 9mm UMP :(

I'd even settle for an MP5 style 9mm clone.

On a side note, the AG has put together a two panels of experts (term used VERY loosely), one to report all the positive aspects of allowing suppressors and SBR's in Michigan. Then also a panel to report what negative affects it would have.

When they finish, years from now, he will use that to help make is decision.

Personally, I can't think of too much negative. It's just a waiting game now.
Yeah no kidding, I'm sure people that are going to take the time and register/pay the tax arent the people we have to worry about. The criminals will do it anyway so why not let the law abiding citizens do it?
 

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I can't wait to see how this project turns out. I'm half tempted to shell out the money if I can find the parts.
 

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Discussion Starter · #8 ·
I can't wait to see how this project turns out. I'm half tempted to shell out the money if I can find the parts.
Heh trust me if you actually find the parts you'll be so psyched that the money wont matter LOL
 

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Discussion Starter · #9 ·
Ok well here are the results of the bolt comparison (with pics of course :))

USC 45ACP Bolt 9mm UMP Bolt
Overall Height: 1.945" 1.945"
Logo Side Height:1.045" 1.042"
Pin Side (Opp): .487" .525"

Just by trying to insert the bolt into the USC it was plain to see where the issue was but it never hurts to double check :) Rounding the USC pin side measurement measurement up to .490 that means we have to take ~ .035" off the 9mm bolt to make it fit the USC. Now obviously if you are doing this yourself go right ahead but for measurement variance I recommend giving your machine shop BOTH bolts (remove the firing pin/retaining pin first) so they can simply match the 9mm bolt to the 45 so there are no issues.

The area where the material needs to be removed is inside the red rectangle :)
 

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Discussion Starter · #10 ·
Well after deliberating and talking to a few machine shops (that really didnt want to touch it lol) I'm sending my bolt to Ed at HDPS to be machined. As soon as it comes back I'll update this post, I'm still waiting on the final piece anyhow; the barrel.
 

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Discussion Starter · #11 ·
That'll teach me to update a thread before I check to see if new parts have arrived! I recieved my 16" 9mm Top-Notch Barrel about an hour ago and I must say I'm pretty impressed. It looks to be very high quality and the price was incredibly reasonable. I'll be grabbing the digital calipers in a few to compare it to the HK 9mm 8" Barrel just to make sure I'm not going to have any issues :)

Here are some pics of the Barrel:
Top is HK 9mm 8"
Center is TN 9mm 16"
Bottom is HK 45ACP 16"
 

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Discussion Starter · #12 ·
Ok checked the TN barrel all measurements were within .005" of the 8" HK barrel so it should be good to go. EDIT: The Chamber at the front was actually very out of spec, TN is going to fix this for myslef and anyone else needing one .

One thing I did notice was that the HK Barrell had flutes, the TN unit did not. I dont think this will make a huge difference but we'll see!

For those of you who like gratuitous parts pics here are some parts that are being used in this little operation:
Shown here top to bottom is:
UMP 9mm Recoil Spring/Firing Pin/Spring
USC 45 Bolt/Recoil Spring
HK UMP Front Accessory Rails
UMP 9mm Barrel
TN 9mm Barrel
HK UMP Optics rail
USC Reciever
HDPS Stock Block "B" With HK UMP Stock
UMP 9mm 30Rnd Mag
UMP 45ACP 25 Rnd Mag
USC Lower with 10 rnd mag
USC Stock/Grip

Not shown:
9mm Bolt
UMP 0,1,F Lower
 

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I'm sure keeping an eye on this. I want to hear how it turns out.

I'm high interested in a 9mm USC/UMP conversion. I've asked about everyone I know in law enforcement to try and help me track down this bolt.
 

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Discussion Starter · #14 ·
I'm sure keeping an eye on this. I want to hear how it turns out.

I'm high interested in a 9mm USC/UMP conversion. I've asked about everyone I know in law enforcement to try and help me track down this bolt.

Ha you and me both, the waiting is the hardest part really..
 

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Discussion Starter · #15 ·
Welp its done! (Almost ;))

Last night we machined my upper reciever and lower grip to fit and function together and I couldnt be happier! We did all the UMP style machining EXCEPT the side vents as we didnt have time to write the CNC program for that process (12:30am comes quick around here). I will of course post pictures of the gun and mods when I get home. I figured I'd share some of my notes that may make this process easier for anyone attempting this on thier own.

Bolt Machining- Since this is a hardened part and is VERY expensive (at least for my 9mm bolt hehe) I HIGHLY recommend shipping it to Ed at HDPS. His price is very reasonable (I believe ~$85) his process is PERFECT as no heat is transferred to the bolt during machining and his service is EXCEPTIONAL (I think Ed and Adam Webber have the same customer service playbook; they rule!) When I Got my bolt back it measured EXACTLY .487 on the pin side just like the stock bolt.

Lower Machining - This was actually the trickiest part, opening up the clips to 7mm is no easy task, if you dont have the tools I recommend sending this to Ed as well. Dont forget to remove the rear "nib" that holds the UMP rear buffer plate on as well or your stock block will be a PITA to make fit.

Upper/Mag Well Machining - This was probably the easiest part, using the template above will result in a perfect fit for all magazines if followed to the letter. We deviated a bit on the curvatures a bit and while the 45 Mags still fit perfectly I did have to hand file a smidgen to make the 9mm Mags fit.

Barrel Pin- While getting the barrel pin out the first time was cake, getting it back in (at least for me) was a little bit of a pain. I'm going to machine the upper to accept the TN quick change barrel pin, honestly I think this is going to be a MUST for those of you who have multiple caliber setups like this; it's SOOOO much easier!

I'll post up any other info I remember between now and when I post pics but those are the highlights. I hope this helps someone out!
 

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Congrats on finding the parts and going through with the 9mm UMP build. I refuse to pay $1500+ for one bolt assembly, otherwise I would have done one a long time ago. I wish someone like Ed or TN would step up to the plate and make a few bolts for us instead of having to get bent over by the parts dealers.

Thanks,
James
 

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Welp its done! (Almost ;))

Barrel Pin- While getting the barrel pin out the first time was cake, getting it back in (at least for me) was a little bit of a pain. I'm going to machine the upper to accept the TN quick change barrel pin, honestly I think this is going to be a MUST for those of you who have multiple caliber setups like this; it's SOOOO much easier!
Can you expand on what machining you're doing to the upper? I too have decided that there must be a better way to swap barrels than using a hammer and punch. I wish someone would make a threaded pin with a sling loop on one end. That would give you something to pull on to get the pin out because it will have to be tight to maintain tolerances...

BF
 

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Discussion Starter · #18 ·
Yeah threaded would be nice ;) You just have to enlarge the plastic part of the barrel pin hole to fit the head of the new pin, no biggie.
 

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Discussion Starter · #19 ·
Well theres good news, and bad news ;)

Good News:
Everything we machined/altered works flawlessly!

Bad News:
The TN Barrel is out of spec.

Well I FINALLY got a chance to shoot this thing today and man was a I geeked! First few shots felt great then I thought my mind was playing tricks on me as I could swear I was feeling significant differences in recoil between shots. My mind wasnt playing tricks after all, the next shot did what you'll see below and then a few more rounds and then the same thing. This was on hot Fiocchi 115GR FMJ ammo.

Then I switched to some less powerful 147GR Hornady rounds and it made it about 2 rounds out of 25 and the spent casing just lodged in the barrel. So after trying my damndest to pull the charging lever back and unlock the extractor (man these suckers are tight! :)) I had to grab a cleaning kit rod and pound it out, that was the end of the trip. Needless to say I should have checked the barrel more! :)

When I was assembling the gun for the first time, I used my snap caps for cycle testing EVERY round would get lodged in the barrel and have to be forced out with a rod. Now normally I would have stopped right there but I attributed this to being a fresh "tight" chamber and my snap caps being pretty beat up. I hand cycled a few rounds of Fiocchi and it fed/ejected properly so I figured I was golden; obviously I was wrong.

When I got home I put a snap cap in with my fingers and put the barrel vertical and it just stayed there. Then I tried the same thing with the HK Barrel and they fell out every time so the barrel is definately the problem.

I'll be calling TN tomorrow to see what they can do for me, in the mean time I'm going to continue my quest of begging Ed at HDPS to make me a fake can for my 8" HK Barrel so I can enjoy the polygonal and flute setup :D

When the gun DID function it was a tack driver, at 40 yds not even really trying (just trying to cycle check) I had a group about 1.5" round.

Overall other than the Barrel I'm very happy and I am definately looking forward to getting this fixed. I have a bunch more info/pics to post but I'll post when its done and 100% functioning.
 

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Discussion Starter · #20 ·
I talked to Wade at TN today and he was great on the phone as usual, I'm going to ship him back my barrel and hes going to take care of it for me :) Great service, I can't wait to get this thing back up and running.

On another note, I converted the Gun to .45 yesterday morning and took it to the range and man is that thing fun! As soon as this is all over I'll post up the final details/pics ect thanks for your patience!
 
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