HK USC to UMP Conversion

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Tactical Excellence on Patrol with Glades County Sheriff's Department.  Click above button for letter from SGT. Hardin, owner of conversion #3.

The HK USC to UMP conversion is no longer available from Tactical Excellence Inc.

This page will continue to be posted in one form or another to document what was considered by many to be the best USC conversion available.

Our thanks to all that have purchased HK USC to UMP conversions.


This Conversion is for the HK enthusiasts who wants as close a copy to the HK UMP as they can get.  All key HK parts and minimal modifications.  If you want the best, this is it.


Conversion Description

Tactical Excellence can take your HK USC and make it more like an HK UMP.

We do this by adding an HK UMP Lower assembly and stock to your USC.  This is done with our specially designed rear conversion block.  The block, made from 7075 aircraft grade aluminum, attaches the UMP lower to the USC receiver and has a hinge and latch assembly for the UMP stock.

With this conversion you now have a comfortable pistol grip, a folding stock, and use UMP high capacity magazines. 

No Tools required to field strip.  With this conversion you no longer need to use the USC tool to field strip your rifle.  This conversion uses a Steel attachment bolt with a sling loop which adds a receiver sling point like the HK UMP.  Field stripping is made simple.  Remove this Sling loop / Bolt with your fingers and the entire lower swings away allowing the recoil spring and bolt assembly to be removed. 



Conversion Details

The following is what is done with your parts to complete the USC to UMP conversion:

USC Receiver

The USC receiver will have a little material removed around where the magazine seats for proper fit of the UMP magazine.  Customers may also option to have vents milled into the forearm of the receiver and the receiver dyed black to better resemble a UMP.

UMP Lower

Any variation of UMP lower receiver can be used with our conversion. 

The UMP lower receiver will have the front hooks modified to fit the USC receiver, a small locking tab removed, and a block permanently installed where the Auto Sear (Release Lever) would go.  Your USC fire control parts will be installed.  4 position lowers and 3 position lowers with burst will have a small notch added to the holes the selectors goes in to allow use of your USC parts.  This notch is not visible when lower is assembled.  3 and 4 position lowers will have the USC left side selector remarked to line up with the UMP pictograms.  UMP left selectors are not compatible with the other USC fire control parts.  The right side UMP selector will be used as this part is the same as the USC but only marked different. You will not be able to move your selector past the semi-auto position to a full-auto or burst position.  Only customers having a Non-SBR conversion done will have a U.S. made trigger installed.

More information on UMP lowers

All UMP lower receivers are designed to use an auto sear (Release Lever) no matter what fire control configuration they may be.  In all modes of fire, the auto sear (Release Lever) is used to keep the hammer cocked until the bolt is fully closed.  This allows the gun to fire in it's various auto modes and in semi-auto the auto sear (Release Lever) acts as an added safety.  There is no provision on the USC for the auto sear (Release Lever) so the USC uses other parts for added safety that semi-auto only UMP lowers do not have.

Using semi-auto UMP fire control parts without an auto sear (Release Lever) removes a level of safety designed in at the factory.  Using USC fire control parts keeps that extra safety.

This is why we install your USC fire control parts into your UMP lower with this conversion.

UMP Stock

The UMP stock will have no modifications made to it.

UMP Magazines

Customers having an SBR conversion done will have no modifications made to their magazines.

Customers having a Non-SBR conversion done will have the base plate and follower replaced in their magazines with U.S. made parts. Parts for 3 magazines are included in price.  If you need parts for more then 3 magazines we can supply needed parts for an additional cost.

UMP .40 S&W bolt

UMP .40 S&W bolts require machining to fit the USC receiver.

UMP .40 S&W barrel

The UMP .40 S&W barrel will have no modifications made to it.

Using Stocks Made by other then HK

Until recently, all of our conversions have been done using HK produced UMP stocks.  One of our customers sent us a Top Notch (TN) manufactured UMP style stock to see if it could be used with his conversion. After examining the TN stock, we found that the TN stock is not a direct replacement for an HK UMP stock, but it can be modified to work with our conversion.  By using a TN stock, the stock will count as one of the 3 needed U.S. made parts in a Non-SBR conversion.  For more information on using a TN stock with a conversion, click HERE

HK UMP Parts Sellers List

Below is a list of companies that  state that they have HK UMP parts for sale and have allowed us to list them here.

Tactical Excellence Inc. does not guarantee the availability or quality of parts from these sellers.  We include this information for the benefit of HK enthusiasts.

International Police Supply

IPS  has a large selection of HK parts and lists UMP magazines, stocks, and lowers that you will need for your conversion.

Email before ordering for availability and current pricing.

Another company with a good selection of HK parts needed for your conversion.

E-mail Adam before ordering for availability and current pricing.


Or give him a call at 801-440-5060



Below are links to pages for the tests conducted during the development of the

USC to UMP conversion



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