UZI Talk - Full Auto Conversions: Mini UZI

UZI Conversions - Mini UZI

The semi automatic Mini UZI Carbine did not enter the US until 1987 - after the May 1986 ban on new transferable machineguns - so the variety and number of converted IMI Mini's is limited. The Mini UZI SMG was in the US before 1986 as dealer samples so there were some around for class II dealers to copy. One option they had before 1986 was to chop down the receiver on a full size UZI in the same way that Vector chopped down some of the full sized Group Industries receivers. These guns are referred to as "re-welds" (from the fact that the receiver had to be welded back together after being cut down) and Fleming did some conversions this way..

Sears:
Fleming also did some registered sears for the Mini UZI that are permanently married to the receivers. Fleming was registering regular UZI SMG sears before 1986 then installing them after 1986. He would install them in a full size UZI by removing the bolt blocking rail, or in the Mini UZI by relieving the trunion to accommodate the "feet" of the factory open bolt. ATF stopped him from doing any more in 1988, so there was a window from 1987 to1988 when these Mini's were done. This is the only option to have a fully transferable IMI Mini UZI that has the relieved trunion and is not a re-weld. While there is nothing wrong with most re-welds, this is the closest you can possibly get to a factory Mini UZI SMG that is fully transferable.

Qualified also made some registered sears that were not married to any receivers but they are extremely rare.

Bolts:
The most common of the Mini UZI conversions is the registered bolt. These were made by cutting down registered full size UZI bolts and therefore most of them do not have the two feet on the front of the bolt. In addition to missing the feet, the front of the bolt has to be re-welded

So just what are those feet? The "feet" are the two rails that project out the front of the bolt. When the bolt closes, those feet tuck inside two holes at the bottom of the trunion. IMI chose this design because it allowed them to reduce the length of the receiver and the overall weight of the gun, both of which were important design goals of the Mini UZI. The sear stops the bolt on the front of those feet, ensuring that the bolt face is far enough back for the gun to cycle properly. But what happens on a converted bolt with no feet? Let's take a look.

Full Size UZI:

For comparison, this is a picture of a full size UZI with its bolt charged. Notice how much distance there is between the bolt face and the back of the dummy round. This ensures that the bolt gets a "running start" and has plenty of momentum to strip off the first round.

Factory Mini UZI:

Here is a Mini UZI with a factory open bolt with feet. The bolt face is not as far back as the full size UZI, but it's well back from the rim of the case. (You can judge the distance by noting how much of the ejector is visible.)

Mini bolt with no Feet:

A Mini UZI bolt that doesn't have the feet will still run fine but there is one problem. To avoid malfunctioning on the first round, the bolt should be forward when inserting a loaded magazine.

This photo shows a bolt with no feet in a Mini UZI using a proper SMG sear. Since the magazine was inserted when the bolt was back, the first round is tilted up severely and will jam.

Mini bolt with no Feet:

This picture shows a Micro UZI (which uses the same size bolt as the Mini) with a bolt without feet and a semi sear. Note that the bolt is even farther forward (as can be seen by almost none of the ejector showing.) This happens because the semi sear pads are not as wide as the SMG pads, allowing the bolt to move father forward. Reliability is better with the proper SMG sear.

Mini bolt with no Feet:

This photo shows what happens when the magazine is properly inserted with the bolt closed and then the bolt is cocked. Instead of tilting the first round up, the bolt pushes the first round ahead slightly. Since it's not tilted at an odd angle, it will feed properly.

Trunions:
In order for the bolt feet to function properly, there has to be a hole on either side of the trunion for the feet to slip into. Without the holes there, the bolt face cannot completely close on the barrel chamber and the gun will not fire. The Mini UZI and UZI Pistol to not have a bolt blocking bar in the receiver like the full size UZI and it's the trunion holes that legally distinguish a semi automatic from a full auto. Adding trunion holes to a semi automatic Mini or Pistol is considered manufacturing a machinegun and is currently restricted to class II dealers for creating dealer sample guns. Here's a look at some of the different trunions:

Semi Auto: The Mini UZI trunion is skeletonized to reduce the weight. This IMI semi auto trunion does not need to be milled out because it's made to run with a closed bolt, which have no feet.	Full Auto: The trunion on a full auto IMI Mini UZI has a notch milled out on each side of the trunion. That allows the feet on an open bolt to rest alongside the trunion. Without these notches, the bolt would not close all the way.	Vector: The Vector Mini UZI is actually a cut down full size UZI and it has a trunion from a full sized UZI, which is not skeletonized. The Vector trunion has two notches milled out just like the full auto IMI. This is allowed because the receiver is already registered as a machinegun.

Note that while the trunion on the semi automatic Mini UZI is not milled out for the feet, the rounded shape of the trunion does leave a gap on either side. Another conversion possibility is to take a registered factory open bolt for the Mini UZI and narrow the insides of the feet (rather than cut them off) so they slide into the smaller gaps in the semi Mini UZI. Although this is a nice solution, it's not something you're likely to see because the semi Mini UZI's didn't arrive in the US until after the May 1986 end to new transferable machineguns, so people typically didn't bother registering any of the factory Mini UZI open bolts. It is possible to do this by cutting down a full size registered bolt to Mini UZI size and manufacture these feet in the process. It will then fit in an unmodified Mini Uzi receiver.

Barrels:
Unlike the full size UZI, the inner dimensions of the Mini UZI trunion are not smaller on the semi automatic than on the SMG. Only the barrel restrictor ring prevents an SMG barrel from being used in the semi automatic. Below are three Mini UZI barrels. The top barrel is a factory semi automatic barrel for the Mini UZI Carbine. Note that there is no secondary barrel band so the barrel is supported by the band behind the flange and the tapered end for the barrel restrictor ring.

The middle barrel is a factory IMI Mini UZI SMG barrel that has had the chamber end turned down to go in the barrel restrictor ring. Again, unlike the full size UZI, this is the only modification needed to fit in an unmodified semi automatic Mini UZI receiver.

The bottom barrel is an unmodified factory IMI Mini UZI SMG barrel.

Vector Mini UZI (Registered Receiver):
Fortunately for UZI enthusiasts, Vector has come to the rescue by making more Mini UZI's available to the transferable market. These were done by taking some of their transferable Group Industries receivers and modifying them to Mini UZI SMG specifications. Here are some of the details:

The full size IMI or Group receivers were not designed to accept the "feet" of the Mini UZI open bolt. Vector had to cut holes in the side of the receiver to make room for the feet.

On some Vector Mini UZI's, holes were left in the receiver for the feet to poke through. This example shows where they did weld over the holes. The vertical circle shows the area that was cut and re-welded.

This is an early Vector Mini UZI where they were trying to copy the rear ribs of an IMI Mini UZI SMG. They had to stop short to not mess with the original manufacturer's markings. A real IMI only has 1 long rib on the left side rather than two.

The long vertical circle shows approximately where this receiver was re-welded.

This is a Fleming Mini UZI Conversion showing the left IMI rear "rib". Fleming had them engraved this way rather than the factory which is just "MINI UZI".

Here's the right side of the Vector Mini UZI with two small "ribs". Also note the use of the Model A style sights. The early IMI Mini UZI's had these sights but all of the Mini UZI's (semi automatic and SMG) shipped to the US had the Model B style sights. Vector does offer the Model B style as an upgrade.

IMI Mini UZI's have two long "ribs" on the right side of the receiver Also note the Model B style sights found on basically all Mini UZI's shipped outside of Israel.

The Vector trunion is actually a trunion from the full size UZI. It also uses the Model A style sights.

The IMI Mini UZI trunion is "skeletonized" to reduce weight. Also note the factory correct Model B style sites.

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Bolts: The most common of the Mini UZI conversions is the registered bolt. These were made by cutting down registered full size UZI bolts and therefore most of them do not have the two feet on the front of the bolt. In addition to missing the feet, the front of the bolt has to be re-welded

Bolts:
The most common of the Mini UZI conversions is the registered bolt. These were made by cutting down registered full size UZI bolts and therefore most of them do not have the two feet on the front of the bolt. In addition to missing the feet, the front of the bolt has to be re-welded