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Discussion Starter · #1 · (Edited)
Does the USC Trigger group fit in UMP NAVY OR FBI LOWER?

With or without any Modification to the lower?
Thanks
 

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yes it does. When you do the conversion this is one step you want to take to keep the gun legal. I'm not sure what, if any modification is needed though...I had Ed at hdps do my conversion and he had to use the USC fire control group in the UMP lower.
 

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I wanted to know the same thing but for the 4 Position Trigger group this does not make your gun full auto?
 

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The USC won't fire full auto even if you attach an unmodified UMP lower to it.
Correct. I saw a clarification letter (can't find the dang thing now though) stating that as long as the receiver isn't modified (by removing the material that blocks a lower with the trip lever still installed from being attached) that the full auto UMP lower is fine to install.

If you want to be overly cautious, when you remove the trip lever and catch parts, fill the area of the lower with JB Weld, preventing the full-auto parts from being reinstalled.

Just watch out for 922r compliance if you don't SBR it.
 

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yes it does. When you do the conversion this is one step you want to take to keep the gun legal. I'm not sure what, if any modification is needed though...I had Ed at hdps do my conversion and he had to use the USC fire control group in the UMP lower.
how much Ed at hdps charged for the coversion from usc to ump lower?
thanks
tony
 

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how much Ed at hdps charged for the coversion from usc to ump lower?
thanks
tony
There are too many options to say - like which lower you want, if you need compliance parts or are going to register it as an SBR, and which style of USC you have (grey or black).

Here's a link to his site with the pricing breakdown.

http://www.hdps.org/htm/5-3-1.htm

Depending on which parts you buy from him and which you buy elsewhere, you're looking about $200 for the block, $175 for the stock, $225 for the lower, and then you'll need some UMP magazines.
 

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If you use a 3-position or 4-position lower, the white lines on the selector levers won't match-up. You'll have to remark the selector levers.

If you use the 2-position FBI lower, the markings line up perfectly.
 

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The safe and fire positions are marked at different "positions" between the lowers even though the lever is in the same spot:

A picture is worth a thousand words:



 

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The kit will work fine... but from the images in the previous post, take the selector lever that you see in the 2-postion lower and picture it in the 3 or 4-position lower -- the lines will not line up with the images. You'll need to cosmetically alter the selector lever.
My lower isn't here yet, so I can't figure out for myself, but why can you not just use the internals from the UMP lower (minus the trip lever and catch, of course)?

I read something about the USC lower having parts that take the place of the catch for safety purposes, but it wasn't specific as to what they are.

Will it only work with the USC internals?
 

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My lower isn't here yet, so I can't figure out for myself, but why can you not just use the internals from the UMP lower (minus the trip lever and catch, of course)?

I read something about the USC lower having parts that take the place of the catch for safety purposes, but it wasn't specific as to what they are.

Will it only work with the USC internals?
I can think of a couple of reasons to use the USC internals. First, the USC trigger pull is a lot better than the UMP trigger pull. Plus, some of the parts in the UMP lower might be considered by some to be "machine gun" parts, even if they won't make the USC fire full auto. Simpler to just avoid any potential hassle and use the USC internals.

Regarding the selector markings, you can see the lowers here.

http://www.internationalpolicesupply.net/hkparts-ump.htm

On the FBI and USC lower, both the safe and fire pictograms are below the selector and the white line points to the bottom of the selector lever. For the 3 and 4 position lowers, safe is actually above the lever and the white line points toward the top of the lever. If you use the USC lever with the 3 or 4 position lower, you'll have the white line pointing down toward one of the firing pictograms even when the gun is on SAFE, unless you remark the lever.
 

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can a UMP(clone) be converted into an auto??

what is this one

http://www.gunbroker.com/Auction/ViewItem.asp?Item=88346724
Of course it can. Just swap a few parts, cut the receiver a little here and a little there, and BAM! You're well on your way to 3 squares and an hour or two a day in the exercise yard.

KATO-EO!

Ohh, you meant legally? Nope. Not unless you are an FFL, and have a letter from a PD (as is mentioned in that post you linked).
 

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Plus, some of the parts in the UMP lower might be considered by some to be "machine gun" parts, even if they won't make the USC fire full auto. Simpler to just avoid any potential hassle and use the USC internals.
EXACTLY! As soon as some LE sees the F/A pictograms or flips that selector lever to aynthing other than S/E, BAM! POW! SHZAM! -- your gun is probably off to the lab for disassembly and evaluation.

A guy here in michigan went and regsitered his USC conversion (don't ask, but anything with an overall length of less than 26" must be reg as a handgun here in Mich). Make a long story short, he got the thing confiscated. I think he eventually got it back but who needs the hassle?

When I did my SL8/G36 conversion, I put the SL8 internals in and remarked the levers... to avoid that same hassle.
 

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EXACTLY! As soon as some LE sees the F/A pictograms or flips that selector lever to aynthing other than S/E, BAM! POW! SHZAM! -- your gun is probably off to the lab for disassembly and evaluation.

A guy here in michigan went and regsitered his USC conversion (don't ask, but anything with an overall length of less than 26" must be reg as a handgun here in Mich). Make a long story short, he got the thing confiscated. I think he eventually got it back but who needs the hassle?

When I did my SL8/G36 conversion, I put the SL8 internals in and remarked the levers... to avoid that same hassle.
I hear of stuff like this all the time, but it always seems to be in other states. (Ok, except for Waco.)

The only one that's ever asked to see my MP5's form 4 is the one indoor range in Dallas that allows full-auto, but I've shot it at many other ranges in semi-mode, but no one's ever even given it a second look. Well, there are lots of "Is that a... no, it couldn't be... is that an MP5???", but no one's ever wondered if it was an illegal SBR, and it has burst pack on it, so anyone might wonder if it's select fire.
 
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