Uzi Extractor

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Dirk Hawthorne

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Has anyone bothered to just pull one out of a parts kit bolt?

I have 4 or 5 kits with the white inspection paint meaning they were NOS when torched.

Most kits even used that I have seen had more handling marks then shooting wear.

Would seem the best & easiest way to get a extractor and not be all hung up on what's what & over thinking things.

that sounds dull
 

Member13

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Not trying to kick a dead horse but: That is still too dang expensive though! There has to be a way to manufacture these things, firing pins and other consumable type steel parts in the good old USA, at a better price. I mean, all you guys here are magicians and experts at different types of industry. I'd throw in some cash on a venture of some sort. I'm not a fabricator unfortunately, except for kydex LOL

you must have not seen the $200 feed ramp fiasco
 

JackFlak

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you must have not seen the $200 feed ramp fiasco
Oh man, that doesn't sound good at all! It all reminds me of that scene in that sequel to the film wall street. Something about a tulip bulb, prices went completely bananas on it, yada yada. I give up. Who wants all my UZI parts LOL
 

Member13

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just got to stick in there and remember that right now is "the good old days" and things are only going up in price

Bowman is allegedly bringing in more Uzi parts kits so there is hope that availability will keep the price at what it is now
 

amphibian

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Not trying to kick a dead horse but: That is still too dang expensive though! There has to be a way to manufacture these things, firing pins and other consumable type steel parts in the good old USA, at a better price. I mean, all you guys here are magicians and experts at different types of industry. I'd throw in some cash on a venture of some sort. I'm not a fabricator unfortunately, except for kydex LOL
I am on an FFL / SOT specializing in making barrels for other manufacturers. I have friends that have seen all the machines in the shop saying you guys should make X, Y etc... Then I show them what each machine is doing and the specialized fixturing involved in just making barrels alone as well as all the setup time. It isn't easy to switch gears like that. We have a bay for prototyping but that is extremely time consuming and not for doing anything at scale. I personally don't have any experience making a 'leaf spring' type extractor like the UZI uses and no idea what is involved but say someone does tool up to do it, I think almost everyone is always going to value an IMI extractor spring over a US made one even if the IMI one is 20+ years old vs a brand new US made one.

Maybe the IMI ones are truly dried up...who knows. Or maybe there is a huge stock in Croatia for the Croatian made Ero which is interchangeable with IMI UZI's. What if someone brings them in from there? I wouldn't want to tool up to make some part and then someone imports a ton of them that are military grade from IMI or from Croatia or even the South African Lyttleton ones are all high quality.

If I needed an extractor, I would pay the $65 now vs waiting for them to be +$100.
 

JackFlak

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I am on an FFL / SOT specializing in making barrels for other manufacturers. I have friends that have seen all the machines in the shop saying you guys should make X, Y etc... Then I show them what each machine is doing and the specialized fixturing involved in just making barrels alone as well as all the setup time. It isn't easy to switch gears like that. We have a bay for prototyping but that is extremely time consuming and not for doing anything at scale. I personally don't have any experience making a 'leaf spring' type extractor like the UZI uses and no idea what is involved but say someone does tool up to do it, I think almost everyone is always going to value an IMI extractor spring over a US made one even if the IMI one is 20+ years old vs a brand new US made one.

Maybe the IMI ones are truly dried up...who knows. Or maybe there is a huge stock in Croatia for the Croatian made Ero which is interchangeable with IMI UZI's. What if someone brings them in from there? I wouldn't want to tool up to make some part and then someone imports a ton of them that are military grade from IMI or from Croatia or even the South African Lyttleton ones are all high quality.

If I needed an extractor, I would pay the $65 now vs waiting for them to be +$100.
Roger that. I'm mainly trying to create levity, I do understand what you're saying. We'll all get through this
 

redweirdbeard

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redweirdbeard

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Here they are. 45 is stamped on both of them. So does that mean I can’t use them for my 9mm. Sorry I’m brand new to this platform.
 

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JackFlak

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Here they are. 45 is stamped on both of them. So does that mean I can’t use them for my 9mm. Sorry I’m brand new to this platform.
Hey man, check the first page of this thread. Lots of good info on this exact topic. I'm not gonna weigh in my opinions, but again the other respected members have made some good points on this - cheers
 

ATCDoktor

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If anybody is interested this is how extractor’s were delivered to the German military back in the 60’s:



I picked these up at a SAR Show 14 or so years ago and can’t remember who the vendor was (most probably RTG).

They came in a package of 4, they are unmarked, still coated in their factory preservative and in 15 years I’ve only had to use one.


I would hate to know I had to build one from scratch.
 

Chef

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I believe we are applying a modern mindset to this extractor issue, where (like with cars and appliances), when a part starts to fail, we replace the entire component instead of rebuilding it.
As long as the claw is intact, wouldn't it be easier to just anneal the old extractor, re-bend it to the proper shape and then re-harden it to restore it's "springyness"?
I imagine if someone did a rockwell hardness test on a new one, the hardness could be replicated on the reshaped one.
 

dustindu4

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When they break the claw tooth breaks off, the rest is encapsulated inside the bolt. Theres nothing to reanneal or harden. Just the tip is exposed.
 

Dirk Hawthorne

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I believe we are applying a modern mindset to this extractor issue, where (like with cars and appliances), when a part starts to fail, we replace the entire component instead of rebuilding it.
As long as the claw is intact, wouldn't it be easier to just anneal the old extractor, re-bend it to the proper shape and then re-harden it to restore it's "springyness"?
I imagine if someone did a rockwell hardness test on a new one, the hardness could be replicated on the reshaped one.



A lot of guys in the gun fraternity will tell you that spring creep isn't a thing. Every textbook about material science on earth will tell you it IS a thing, however.

Spring creep and wood finishing are the two twilight zones of the gun world.

The only extractor I had to replace lost it's "springyness" due to creep.

I don't see why it couldn't be re-bent. I'll look into it and report back.
 

Generalzip

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It's actually not creep. It's a phenomenon called stress relaxation. Creep is when strain occurs in a material under constant stress/load. Relaxation is a change in stress/force while maintaining a constant strain. In the case of the spring you strain it to whatever compressed length and it sits there a long time. During this time the spring essentially suffers from some plastic deformation while the stress is under the tensile stress of the material. This is why creep and relaxation are often confused. They are related phenomena, but different a bit. Additionally when you move a spring back and forth it also undergoes fatigue. Certain alloys are more or less susceptible to fatigue. Additionally, temperature, number of cycles, etc all play a role in how quickly both relaxation and fatigue affect a metal.

Generally what caused failure in a moving part is fatigue. Dislocations in the crystal structure form after many cycles within the elastic range. This leads to an increase in brittleness. Theoretically one could re heat treat the part after say 5000 rounds and this would greatly increase the life of the extractor by relieving any internal stress and dislocations formed in the crystal structure due to fatigue. Realistically, someone should just start to manufacture new quality extractors and make a hell of a lot of money.

Sorry to nerd out on ya. Just in case you or anyone else was curious.
 

navgunner

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It's actually not creep. It's a phenomenon called stress relaxation. Creep is when strain occurs in a material under constant stress/load. Relaxation is a change in stress/force while maintaining a constant strain. In the case of the spring you strain it to whatever compressed length and it sits there a long time. During this time the spring essentially suffers from some plastic deformation while the stress is under the tensile stress of the material. This is why creep and relaxation are often confused. They are related phenomena, but different a bit. Additionally when you move a spring back and forth it also undergoes fatigue. Certain alloys are more or less susceptible to fatigue. Additionally, temperature, number of cycles, etc all play a role in how quickly both relaxation and fatigue affect a metal.

Generally what caused failure in a moving part is fatigue. Dislocations in the crystal structure form after many cycles within the elastic range. This leads to an increase in brittleness. Theoretically one could re heat treat the part after say 5000 rounds and this would greatly increase the life of the extractor by relieving any internal stress and dislocations formed in the crystal structure due to fatigue. Realistically, someone should just start to manufacture new quality extractors and make a hell of a lot of money.

Sorry to nerd out on ya. Just in case you or anyone else was curious.
This is spot on. I serve as an Industrial Advisory Board Member for the Engineering Technology Collage at Oklahoma State University and this is core lesson for our undergraduate students. Good job, @Generalzip.
 

Dirk Hawthorne

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It's actually not creep. It's a phenomenon called stress relaxation. Creep is when strain occurs in a material under constant stress/load. Relaxation is a change in stress/force while maintaining a constant strain. In the case of the spring you strain it to whatever compressed length and it sits there a long time. During this time the spring essentially suffers from some plastic deformation while the stress is under the tensile stress of the material. This is why creep and relaxation are often confused. They are related phenomena, but different a bit. Additionally when you move a spring back and forth it also undergoes fatigue. Certain alloys are more or less susceptible to fatigue. Additionally, temperature, number of cycles, etc all play a role in how quickly both relaxation and fatigue affect a metal.

Generally what caused failure in a moving part is fatigue. Dislocations in the crystal structure form after many cycles within the elastic range. This leads to an increase in brittleness. Theoretically one could re heat treat the part after say 5000 rounds and this would greatly increase the life of the extractor by relieving any internal stress and dislocations formed in the crystal structure due to fatigue. Realistically, someone should just start to manufacture new quality extractors and make a hell of a lot of money.

Sorry to nerd out on ya. Just in case you or anyone else was curious.


I'm a structural engineer with a master's degree in civil engineering.

Let me think on this for a tad.

Here we have a spring (UZI extractor) that's left in its little hidey hole in the bolt for a decade or two.

If it exerts less sideways force on the 9mm case than it did originally, that would be stress relaxation.

If you take it out and it has a different shape than it originally did, it's less bent, that's creep.

Can you have stress relaxation in a spring without creep? What would be an example of that?

If you leave a gun magazine loaded for 20 years and you take the spring out, the spring will definitely be shorter than it was when it was put in the mag. With the creep accounting for the lower force exerted on the follower.
 

Dirk Hawthorne

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This is spot on. I serve as an Industrial Advisory Board Member for the Engineering Technology Collage at Oklahoma State University and this is core lesson for our undergraduate students. Good job, @Generalzip.

It's irrelevant, since I've been told by countless gun guys that spring deformation under load isn't real.

Also, spray automatic transmission fluid on your gun stock. Or any other random chemical you can think of. Don't use actual wood finishing products on your gun stock. Wood finishing has been around for 1,000 years, but it needs to be completely reinvented with random chemicals when it's a gunstock.
 
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