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gunco irregular
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Discussion Starter · #1 ·
There are build totorials on this site like MUSIBIKE's UZI SEMI BUILD STEP BY STEP None of this is new or groundbreaking but figured some more build pictures wouldn't hurt.

Got to shoot a full auto UZI a few years back and was surprised on how controllable it was. Not going to spend $20K to get my own FA UZI, but Christmas before last the Fat Man brought me a $175 Model A UZI parts kit, $75 repair section (922R), $40 USA grip and handguard set (922r times 2), $20 charging handle 922R. Green Mountain was out of cheap barrel blanks (922r), so the kit sat for over a year until GMB sent me an email a few months ago that the blank I wanted was back in stock. So the parts were dusted off and the build was restarted. Still not done with it, but it's done enought that it's been fired a few times which went off without a hitch. Once it's marked I'll submit a form 1 SBR (I hate the long barrel) and down the road when the tax stamp comes the barrel will be shortened to 10.5".

Probably take me a while before this gets parkerized and the form1 gets sent off for, so bear with me.

The Uzi build is similar to an AK build where there is a correct receiver length, but mainly you want the top cover to fit and can adjust the length a little either way to acheive this. Slightly too short and the top cover will bind but it can be trimmed. Slightly too long and the top cover will fit sloppy but can be built up with weld. The UZI drawings show 13.510" for the sheetmetal receiver minus the back plate and front trunnion. That's within .010" or so of where this one ended up after welding. The top cover fits well. The repair sections are slightly shorter than the original receiver, so make sure the bottom and sides are aligned for welding and don't worry about the heigth of the sides. The repair section for this build came with the denial bar already welded in. I made a welding mandrel to hold the back plate, repair section, front stub and semi auto feed ramp in position for welding. The 1/2" stock bolt hole is in line with the barrel bore, so I just turned a piece of aluminum to fit the trunnion, feed ramp ring and threaded it for a 1/2" bolt. Worked like a charm. The ring on the feed ramp needs to be aligned with the barrel and also be tight to the bottom of the receiver. The jig held it there for welding. Pic two the feed ramp hasn't been welded on yet, but the grip mount and handguard mount have.
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gunco irregular
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Discussion Starter · #2 ·
Next up is the bolt. You can buy a complete semi auto bolt assembly, modify your own or a combination of the two. I modified my own bolt, but bought a striker assembly. The bolts are hard enough that you'll either need to use carbide to machine it or anneal the bolt. Most just anneal the bolt, but I'm stubborn and used carbide. You need to: remove the full auto feed lip; drill for a firing pin; slot to clear the blocking bar; open up the bolt hood to clear the semiauto feed ring; build up the rear bolt recess with pins or weld so the firing pin doesn't go any deeper than the rearmost edge of the bolt; modify the extractor to semi auto; remove FA sear notches and add semi auto feet; optional bevel the ejection window.

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gunco irregular
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Discussion Starter · #4 ·
Grip frame modification. The grip housing needs a slight modification so that the selector cannot go into the forward full auto position. This is accomplished by welding in a small tab about .050"-.090" thick that prevents the forward curved arm of the selector lever from going far enough forward into the FA position. Strip the grip housing except for the selector parts. Put the selector in the middle "semiauto" position and scribe a line on the front side of the selector arm (red line). There needs to be clearance between the front of the tab and the front edge of the grip housing as the sear spring loop rests at the bottom front of the fire control pocket. The tab also cannot go all the way across the grip frame as the grip safety bar slides back and forth on the bottom right of the fire control pocket. The selector arm only reaches to about the middle of the grip frame so there's no need to go any further than that. Guys have even welded in washers to block the slector travel. I used a .0100"ish piece of scrap steel to make the tab. It had clearance for the sear to swing before welding, but the weld bead stuck up high enough to cause issues. Could of just ground it down with a dremmel, but opted for a skim pass on the mill which did the trick. The tab is the unfinished metal to the left of the red line.
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gunco irregular
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Discussion Starter · #5 ·
The kit the Fat Man dropped off didn't come with a barrel. Semiauto pattern 16"-18" barrels are available for around $150, or you can make one from a $42 barrel blank if you have access to a lathe. Blank: turned between centers; chamber end profiled; chambered to 9mm Nato with Manson reamer; finish profiled and muzzle threaded 5/8"-24tpi.

If you make your own barrel there are barrel drawing online. Choose one that matches your receiver setup Feed ramp ring/FA-semi front trunnion ect. The bolt is supposed to bottom out on the front trunnion and not hit the barrel. For headspace measure from the bolt face to the front of the trunnion (not the lip). There is .022" difference between the Go and NO-GO gauge so compared to a rifle the headspace range is very generous.

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gunco irregular
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Discussion Starter · #6 ·
It still needs some work. The rear sight needs welded in, sling swivel rivetted in, the whole thing abrasive blasted, parkerized and gunkoted. It's done enough to test fire though, 5 mags with no jams after the extractor mod. Kind of expected it needing some tweaking to get it to cycle, but I'll take it. I'll keep posting updates until the tax stamp comes and the long barrel gets cut back to normal length.

Not my pic, but when the feed ring on the FA bolt is removed it can cause an issue with the extractor not snapping over the case rim. The fix is a small bevel on the bottom of the extractor. Mine would feed and eject fine dummy rounds from the right side of the mag, but occasionally jam feeding from the left until the mod was done.

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Looking good, I'm still working on the receiver shell weldup on mine. One small correction though, when you remove the feed lip in the semi conversion of the bolt, the extractor no longer snaps over the cartridge when feeding. With the open bolt, the feed lip pushes the cartridge into the chamber. Once in, the bolt continues on, snapping the extractor over the cartridge and firing the round. This is called push feed and is common in rifles but rare in pistols, only 2 that come to mind are the AMT Automag and the Desert Eagle, both of which have bolts similar to an AR15.

On the semi converted closed bolt without the feed lip, the bolt now becomes a controlled feed system like most pistols. When the boltface impacts the rear of the cartridge in the magazine and shoves it forward, the now flat surface of the bolt allows the rear of the cartridge to slide upward, eventually sliding under the extractor. This would not work with an extended fixed firing pin like on the open bolt, the top of the cartridge case would hit the underside of the pin and jam the gun. Which is why the open bolt uses the feed lip to shove the cartridge ahead of the bolt. And why it's removed on a semi, to make conversion to FA harder and to jam up should the firing pin of the semi be forward when the bolt closes.

BTW, you may have noticed old Uziel kinda stole the extractor design from John Browning's 1911. The modified lower corner is also present on the 1911, allows for easier entry of the round sliding up the boltface. Tons of extractor tuning tutorials for the 1911 on the web, 99% of which directly apply to the UZI extractor as well, should you experience issues.
 

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gunco irregular
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Discussion Starter · #9 ·
Kernelkrink, that is correct on the push feed and controlled feed. I pared down the reason for the extractor mod too much and should of worded it better. Good to know about the 1911 extractor tuning works for the UZI.

Compared to other builds the UZI seemed pretty straight forward, but the jig I made I think helped a lot with that since it holds everything in alignment for welding based off of the trunnion and 1/2" hole in the back plate which should be aligned.

I need to get motivated to fill out the form 1 paperwork to shorten the barrel as shooting it with a suppressor hanging off of the long barrel just looks wrong.
 

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That's why mine is a handgun until/if I decide to SBR it. Got one of the older kits with the OEM subgun bbl included. That's the beauty of "rolling your own", all my rifle builds start out as handguns when possible, the stock is left off until after initial test fire. Remove the stock and put a short bbl on it reverts to a handgun, not an SBR like a factory rifle would. For some weird reason only AFT understands, they ruled back in the day that since the IMI semi UZI rifle was shorter than 26" OAL with the wood stock removed, the QD feature on it couldn't be used. Had to be bolted on, apparently spending an extra few minutes with a screwdriver to remove it versus popping a latch made a difference, especially since the factory folder was the same length folded as the wood was with it removed... In any event, as a pistol converted to a rifle the QD stock can be used.

Grabbed one of the last of the cheap kits a year or so ago, along with a Mini Uzi repair channel. Many many Yahrons ago Centerfire (IIRC) was selling Mini semi bolts and bbls for like $20-30 each. I grabbed a couple bolts and one bbl, knowing what they go for now I shoulda got a second mortgage and bought them out! Anyways, between the kit parts and the actual Mini parts I should be able to piece together a somewhat accurate replica. Hard part is gonna be the folding stock, haven't seen any new replicas in years and originals are even worse than MP5 A3 stocks on pricing. May try to make my own. Long term project though, got too much to catch up on without starting new projects!

Always wanted a Mini since I saw Chuck Norris use his in Delta Force to take out half of the Terrorists in the Middle East! Now all I need is to find some surplus handlebar rockets along with an old Suzuki dirt bike...
 

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Next up is the bolt. You can buy a complete semi auto bolt assembly, modify your own or a combination of the two. I modified my own bolt, but bought a striker assembly. The bolts are hard enough that you'll either need to use carbide to machine it or anneal the bolt. Most just anneal the bolt, but I'm stubborn and used carbide. You need to: remove the full auto feed lip; drill for a firing pin; slot to clear the blocking bar; open up the bolt hood to clear the semiauto feed ring; build up the rear bolt recess with pins or weld so the firing pin doesn't go any deeper than the rearmost edge of the bolt; modify the extractor to semi auto; remove FA sear notches and add semi auto feet; optional bevel the ejection window.

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I just made an account on here so I could ask you- this seems to be the most recent Uzi build post I've found so far online, and I wanted to ask you if you could provide the dimensions of opening up the bolt hood and slot for the blocking bar? With the insane shortage of semi auto bolts on the market, I'm planning on converting the original bolt to semi. I found videos covering a walkthrough for the other steps, but nothing covering the specific measurements for milling away the material. Thanks!
 

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gunco irregular
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Discussion Starter · #12 ·
Welcome to the site DocDorman,

The blocking bar slot is located .220" down from the top of the bolt and is around .285"-.290" wide and .410"-.430" deep. A few thousands either way shouldn't be an issue as long as you have good clearance on your blocking bar.

The bolt hood needs to be opened up to about .840" to a depth of about .3.615". A few thousands either way shouldn't be an issue. I made a little .840" dia x1" long cylinder out of aluminum (the first scrap rod piece I found) and basically just opened it up until the cylinder fit in the bolt hood since it can be hard to measure. The one in the pic ended up about .846" and 3.616" deep. As long as you have good clearance on the semiauto feed ramp ring you are golden.

I didn't anneal the bolt like most people do. I did use a bridgeport type machine and carbide tooling though. It didn't seem particularly hard to machine on a ridged machine. The only area I thought I might have an issue with was milling the right side bolt feet back under the ejection port area where the metal is thin/unsupported and wanted to flex slightly when cutting it in a single pass. I'm fairly certain if I'd of used my drill/mill with the bolt still hard that the end mill would of chipped or broken from the less ridged machine unless the bolt was annealed.
 

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Welcome to the site DocDorman,

The blocking bar slot is located .220" down from the top of the bolt and is around .285"-.290" wide and .410"-.430" deep. A few thousands either way shouldn't be an issue as long as you have good clearance on your blocking bar.

The bolt hood needs to be opened up to about .840" to a depth of about .3.615". A few thousands either way shouldn't be an issue. I made a little .840" dia x1" long cylinder out of aluminum (the first scrap rod piece I found) and basically just opened it up until the cylinder fit in the bolt hood since it can be hard to measure. The one in the pic ended up about .846" and 3.616" deep. As long as you have good clearance on the semiauto feed ramp ring you are golden.

I didn't anneal the bolt like most people do. I did use a bridgeport type machine and carbide tooling though. It didn't seem particularly hard to machine on a ridged machine. The only area I thought I might have an issue with was milling the right side bolt feet back under the ejection port area where the metal is thin/unsupported and wanted to flex slightly when cutting it in a single pass. I'm fairly certain if I'd of used my drill/mill with the bolt still hard that the end mill would of chipped or broken from the less ridged machine unless the bolt was annealed.
I appreciate it man. Your post is an amazing guide for guys like me who are new and learning but still want to get it done the right way. Very informative and easy to understand.
 
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