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And so it begins: 9mm USC to 16" UMP Conversion and links to ALL UMP Conversion Info!

85472 Views 117 Replies 37 Participants Last post by  Gokoolab
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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I know this thread started as a 9mm conversion thread but it would appear its got a bunch of general USC to UMP conversion info too.

Here is an alternative for all you guys bitching about having to buy an expensive barrel as your 3rd 922r compliance part when you have a perfectly good HK factory 16 inch barrel.

Fresh of the CNC machines, the new HDPS US Made Steel Trigger.

http://intrastar.net/~kdogg/guns/hk_uscump/hdps_us_trigger.jpg

No comment on pricing as its not officially listed for sale on HDPS.org yet. I was lucky enough to get my hands on one of the first production runs. Just came in the mail overnight Express. Keep an eye on HDPS.org or contact Ed for more info and pricing.
 

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AFAIK, genuine USC/UMP barrels are not flutted like a MP5....but I might be wrong
I think you are wrong on this one. My neighbor has an issued UMP40 and it has flutes and the same with my UMP40 barrel. The brass looks just like MP5 brass after firing. It might be something else putting the marks on the brass but flutes seem to be a likely cause...

BF
 

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Discussion Starter · #27 ·
I talked to Wade at TN yesterday and he agreed the chamber was off, so hes going to send it back to his manufacturer and have them re-ream it and make it functional. This will likely take at least a week so I'm sitting here waiting again lol In the mean time I'm going to build a G36 clone though ;)
 

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Discussion Starter · #30 ·
Ha! Nope... over a month.. I'm PRAYING that HDPS gets thier fake cans done for the UMP 8" Barrels so I Can use the HK one I have. I'm doing a G36 conversion on the mean time to keep me busy. What a PITA, I wish we could SBR in this state!
 

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Ha! Nope... over a month.. I'm PRAYING that HDPS gets thier fake cans done for the UMP 8" Barrels so I Can use the HK one I have. I'm doing a G36 conversion on the mean time to keep me busy. What a PITA, I wish we could SBR in this state!
I hear ya, I'd love an SBR. I hadn't thought of using a pinned suppressor. Hmmmmm. So how is the recoil on the 9mm UMP say compared to a roller locked gun? Jeff
 

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Discussion Starter · #32 ·
I hear ya, I'd love an SBR. I hadn't thought of using a pinned suppressor. Hmmmmm. So how is the recoil on the 9mm UMP say compared to a roller locked gun? Jeff
Honestly I dont think I can fairly compare YET since the shells had a hell of a time getting out of the chamber. I'm sure that reduced recoil a bit hehe :D When I "think" it shot well it seemed to be in line with my clones.
 

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5 Months later.. still NO replacement barrel from TN... Not a happy camper to say the least.
GTP...how's the conversion going? I was checking out your post and you are getting me really, REALLY interested in one myself. I have been doing a lot of research and it looks like it will cost big$$$$. So, if you don't mind, what was the damage in $$$. Was it tough to get parts? I was thinking of 9mm or 40 SW, but the available of parts will be the deciding factor. I have unlimited 9mm or 40SW ammo from the job, that's why I want 9mm or the .40SW route. Thanks.
 

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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 :)
On here I see that you had to get the 9mm bolt machined to fit in the usc receiver. Does the .40 S&W bolt have to be machined? I am trying to get as much info as possible. I want to get a USC and do the UMP conversion but want to make sure there are no little surprises before i get any parts together.
 

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Discussion Starter · #36 ·
On here I see that you had to get the 9mm bolt machined to fit in the usc receiver. Does the .40 S&W bolt have to be machined? I am trying to get as much info as possible. I want to get a USC and do the UMP conversion but want to make sure there are no little surprises before i get any parts together.
Any of the UMP bolts need to be machined to fit into the USC, Machining them also removes the trip for the sear removing another possible hiccup for the ATF :) As far as the damage in $$$ in concerned I think i've got about $5K in that gun or so.
 
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Im just curious. I just bought the USC 45 carbine and the UMP conversion kit. I know some places fill in the hole for the sear block in the UMP lower to prevent being able to make it full auto. Im just curious why they do this because from what I understand you have to cut some of the plastic from the upper receiver on the USC in order for the sear to catch the trip anyways. Im just curious if im getting screwed by paying an extra $30 bucks to have them fill it in if its not going to work with that part on the upper being cut??


Thanks
 

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It's for piece of mind and liability reasons for the one doing the conversions as a business. Without the block, you could put all the UMP fire control parts back in place, and then do the illegal mod to the upper receiver with nothing more then a red hot butter knife. Then you would have an illegal machinegun. About 15 minuets of work if you take your time.
With the block in place you would need to obtain another lower and do all the mods to fit the USC plus the illegal upper receiver mods. If a person who does conversions for customers found himself in court, he can show that he took extra precautions to keep this illegal mod from being done. By you needing another lower, it shows you bought parts beyond what was needed to do the basic conversion rather then just being able to modify the converted rifle you have and install fire control parts that were already included with parts you had to buy for the basic conversion. You went that extra mile to make an illegal weapon so more guilt is on you.
 
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