Building semi automatic Uzi – Part 4 of 6: Assembling the new receiver

Both Sites, top catch, and barrel catch

Both Sites, top catch, and barrel catch instructions

In the first three posts, we took a brand new semi automatic Uzi receiver and some Uzi parts from a parts kit and painted some of the parts. We also changed out the fully automatic sear for a semi automatic one, and we had a piece of mental welded into the Pistol stick grip to satisfy the ATF rules on converting a fully auto pistol grip/receiver to a semi auto one.

Putting together the Rear Site/Top cover

Before you can install the rear site, you must put the top cover latch and spring in place in the rear part of the Uzi receiver. They go right under where the rear site will be assembled.

These are the parts.  Nut for the real site screw is not shown.

Top cover catch and spring

Parts that make up the top cover latch and rear site.

The latch I got in the parts kit and the spring are shown in the picture below.  They were a little beat up, and I ended up replacing them with new parts.  Also, the surface of the receiver got scratched up when I had to bend the tabs that hold the top catch in place.  Since this area is covered when everything is installed, I didn’t feel I needed to touch it up.

Top cover catch and spring

Top cover catch and spring

Do not push the latch in all the way yet, there is a metal piece that goes over the spring and the latch and snaps on to the ends of the metal tabs.  It keeps the spring and latch under press and keeps it from shooting out from the end of the gun. This is what it looks like:

Screen Shot 2013-12-08 at 6.23.27 PM

This part holds the top cover latch and spring to the receiver and acts as a base for the rear site

The front is at the right. The rear as at the left. Push the catch and the spring in and this snaps over both of them on to the tabs on the receiver.  The little rising area in the top of it is used to give the rear site some pressure and hold it in either of two positions.

Once this piece is in, you can put the rear site into place. There is two holes on the sides of the area where the site goes.  The screw goes through one side, and through the rear site and out the other side. A special nut is then put on the bolt to hold it in place.


rear site assembled above the top cover latch assembly

Screen Shot 2013-12-08 at 6.30.39 PM

The parts that make up the front site

This is three pieces. A washer, the front site , and the front site nut.

This is a hole at the top front of the receiver.Put washers, then nut, then screw in the front site. You can use your fingers to twist it in, or you can buy a uzi front site adjusting tool for fine tuning the site after the gun build is finished.

Barrel and Barrel Catch

If you look at the front of the receiver. Look to the left where the barrel goes. This is a small opening in the receiver, right above the  barrel.  This will hold a Spring and the Barrel Catch.  This device holds the barrel in place.  When installed press the Barrel Catch and then you can unscrew the barrel nut

Screen Shot 2013-12-08 at 6.39.51 PM

Barrel Catch and Spring


barrel catch installed above barrel

Installing the Barrel and Nut


Since this is a semi auto receiver, you can only use semi auto barrels. This receiver has been designed that full auto barrels do not fit. This a a half moon ridge on the top of barrel and there is a similar half moon ridge on the receiver. When place together it fits perfectly. Full auto barrel would not fit.  Once you have the half moons put in the correct positions the barrel snaps into the trunnion with a perfect fit.  You then screw on the barrel nut.  When the barrel nut is almost in place, you may have to press the barrel catch down for the last few turns. When you release the barrel catch, it firmly holds the barrel nut in place.  To remove barrel, you will have to hold the barrel catch down for the first few turns as well

Top Cover alternation to Full Auto Cover

If you are using a semi auto Uzi top cover, then you need to make no alternations.
But if you are using a cover from a full auto Uzi parts kit, then you need to make one change to make it legal.

How can you tell which Uzi top oover that you own. It’s very easy. Pull the cocking handle on the top. Then let go. It should  slide back when you release it.  That’s semi auto.
Do you hear a ratcheting noise and when you stop pulling the cocking, level does it stop without going all the way back, well then you got the full auto top cover.

Some people suggest taking the cocking knob and corresponding assembly on the other side apart. I have a much easier way.

This is what the cocking lug looks like when it take it apart from the top cover (Don’t do it)

Screen Shot 2013-12-08 at 6.59.30 PM

Under normal conditions you could just unscrew the screw in the cocking knob that goes though the top cover and attaches to this cocking lug.  Unfortunately, most of these screws have been staked. They will not easily come out without drilling or ruining the screw.

Look closely at this assembly. There is a wire tab sticking out the front of the assembly. Just take some pliers grab it and pull it off. This is what it looks like:

Screen Shot 2013-12-08 at 6.59.03 PM

Once this wire has been removed, the cocking level should pull back without any pressure, when you release it, it should slide all the way forward.

Here’s a diagram with an arrow pointing to the wire that should be removed.


Top cCover Wire Removal

You are finished with the Uzi top cover modification and the exterior parts on the Uzi Receive.

In the next and final post, we will assemble and install the bolt and finish the build.  I also have pictures and video from the range, where we fired it for the first time.

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