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Mixing Tungsten Powder Into Lead For Higher Ballistic Coefficient


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#1 TTK Ciar

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Posted 16 April 2018 - 1224 PM

Does anyone know if mixing inexpensive tungsten powder into bullet lead has been practiced? Any thoughts on why it might not be a good idea?

Looking at typical prices, fine tungsten powder is only about $15/kg (USD), which corresponds to less than $0.001/grain, which means it wouldn't add much to the material expense of manufacturing bullets (as a filler, not an alloy). A 125gr bullet 50% tungsten by weight would add just six cents to its material cost and increase its density by 35%.

Since tungsten is more dense than lead (19.3g/cc vs 11.34g/cc), mixing it into lead would allow for a lower bullet volume at a given sectional density. This means bullets could be given a deeper, narrower ogival shape without sacrificing sectional density nor increasing their mass nor increasing their length, for an improved ballistic coefficient.

The main problems I can see are (1) the (slight) toxicity of tungsten might put off manufacturers or buyers and (2) getting the tungsten to distribute evenly in the lead might be problematic, and bullets with uneven weight distributions don't spin-stabilize well.

What else?

Edited by TTK Ciar, 16 April 2018 - 1225 PM.

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#2 JWB

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Posted 16 April 2018 - 1328 PM

How toxic is tungsten as compared to lead?


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#3 TTK Ciar

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Posted 16 April 2018 - 1639 PM

How toxic is tungsten as compared to lead?


It's differently toxic, making a direct comparison difficult, but the OSHA PEL for lead is 50 micrograms/meter^3, while for tungsten it is 5 milligrams/meter^3. By that measure it would be less toxic than lead.
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#4 DB

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Posted 16 April 2018 - 1703 PM

Would it not cause barrel erosion unless you used a fairly thick jacket?


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#5 KV7

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Posted 16 April 2018 - 1755 PM

You may as well just make a proper tungsten cored AP round.


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#6 TTK Ciar

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Posted 16 April 2018 - 1928 PM

Would it not cause barrel erosion unless you used a fairly thick jacket?


I wouldn't think so, but could be wrong. The main cause of barrel erosion is hot high-pressure propellant gas, not smooth, slick metal bullets.

You may as well just make a proper tungsten cored AP round.


You could, absolutely, but WHA rod costs six to eight times as much as tungsten powder, and that would add significantly to the cost of the bullet. There would also be a diminished terminal effect, as WHA cores don't fragment in flesh.
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#7 Colin

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Posted 16 April 2018 - 2040 PM

if you are arguing cost, likely you focused on training ammo. People have being playing around with zinc and other products. You could go with a epoxy infused with Tungsten? 


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#8 Simon Tan

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Posted 16 April 2018 - 2317 PM

Sintered tungsten powder cores. Been done. Not cost effective.


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#9 TTK Ciar

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Posted 16 April 2018 - 2338 PM

Indeed, sintering tends to be quite expensive. I'm not talking about sintering, though, merely compounding, using the tungsten powder as a high-density filler.
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#10 EchoFiveMike

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Posted 18 April 2018 - 0843 AM

The use of tungsten in bullets has lead to almost 100% cancer rates in lab rats, so much so that they stopped the test and euthanized all the animals.  It's been covered on TN before.  S/F....Ken M


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#11 Loopycrank

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Posted 18 April 2018 - 0942 AM

If I understand correctly, you are proposing a sort of matrix of lead with very fine particles of tungsten in it.  The idea doesn't seem wildly unsound, and could probably be made to work if engineers banged on it for a while, but I can see a few potential hangups:

 

1)  Lead-cored bullets are typically swaged.  Wouldn't the ultra-hard tungsten powder chew up the swaging dies?

 

2)  Steel is preferred for military bullets since, in the event of an apocalyptic WWIII scenario, there is actually a very real possibility of not having enough lead.  I can't imagine that adding tungsten to the mix helps.

 

3)  The initial pressure/burn curve of the propellants is strongly influence by the inertia of the bullet.  If the bullet is quite massive, it advances into the bore more slowly, which means that the volume available for the propellant gas is smaller, which means higher pressure, which means that the burn rate increases.  The powder needs to be selected with the bullet weight in mind.  Not a big deal for handloaders tinkering in a garage, but it's a big deal for mass-manufacture.  This would probably not be a plug-and-play type of deal.


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#12 JWB

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Posted 18 April 2018 - 1139 AM

The use of tungsten in bullets has lead to almost 100% cancer rates in lab rats, so much so that they stopped the test and euthanized all the animals.  It's been covered on TN before.  S/F....Ken M

That is published here:

https://www.military...r-new-u-s-bombs

 

Except rats aren't humans:

https://www.insuranc...8/30/462789.htm


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#13 TTK Ciar

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Posted 18 April 2018 - 1732 PM

If I understand correctly, you are proposing a sort of matrix of lead with very fine particles of tungsten in it.


Yes, exactly. Tungsten powder is the cheapest form of tungsten, and it would be used strictly as a high density filler -- held in matrix by the lead, not alloyed or sintered.

The idea doesn't seem wildly unsound, and could probably be made to work if engineers banged on it for a while, but I can see a few potential hangups:

1) Lead-cored bullets are typically swaged. Wouldn't the ultra-hard tungsten powder chew up the swaging dies?


That's an excellent point. I don't know, and will look into it.

2) Steel is preferred for military bullets since, in the event of an apocalyptic WWIII scenario, there is actually a very real possibility of not having enough lead. I can't imagine that adding tungsten to the mix helps.


I ran the numbers, and you're right. One ton of tungsten could be made into on the order of hundreds of thousands of bullets, but a serious war would require literally billions of bullets. Most of the world's tungsten is mined in China and Russia, and if that becomes unavailable there simply wouldn't be enough tungsten being produced to satisfy demand.

https://www.indexmun...roduct=tungsten

3) The initial pressure/burn curve of the propellants is strongly influence by the inertia of the bullet. If the bullet is quite massive, it advances into the bore more slowly, which means that the volume available for the propellant gas is smaller, which means higher pressure, which means that the burn rate increases.


While this is true, the notion is not to increase bullet mass, but to keep their mass constant while reducing volume (deepening the ogival nose shape, to increase ballistic coefficient).

A 72gr bullet would remain a 72gr bullet, and would have the same length, but would have a longer, narrower nose part.

I didn't know steel was being used in part to mitigate potential lead shortages. You've given me some things to think about.
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#14 Loopycrank

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Posted 24 April 2018 - 1155 AM

 

While this is true, the notion is not to increase bullet mass, but to keep their mass constant while reducing volume (deepening the ogival nose shape, to increase ballistic coefficient).

A 72gr bullet would remain a 72gr bullet, and would have the same length, but would have a longer, narrower nose part.

 

 

There could be problems here too.  A lot of desirable aerodynamic features in a bullet lead to reduced stability.  A bullet can never be 100% aerodynamically optimal, since it also need to be spin-stabilized and it also needs to form a seal with the bore.  Compromise is inevitable.


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#15 GregShaw

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Posted 24 April 2018 - 1341 PM

Staying at the same weight isn't going to work. Most small arms are overall length limited, so you can't do much to the ogive while remaining under OAL and full caliber to the case mouth. You also need to keep a minimum parallel bearing length for stability in the case and for the rifling to grab. Lead core 7.62x39 already has very limited length inside the case mouth, I don't know if you would be able to stay at 122ish grains and still have any bearing surface.


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