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Over in the Optimum Projectile Size thread of ZDP-189's excellent blog, Dan and Aaron had both mentioned being intrigued on past occasions with the unique properties of high-density Tungsten as a possible slingshot ammo, but that it's being "fabulously expensive" rendered it impractical. I was immediately curious, and began doing a little research, and because said research was becoming a bit too off-topic to a blog thread about optimal shot sizing, I've opted to repost the info here in the main forum, where more people can see it and get involved.

Advantages of Tungsten-Carbide Shot:

a) Density:

Hunters are well acquainted with the advantage of lead (11.3 gr/ccm density) over steel (7.8 gr/ccm) - with a 45% greater density, it's significantly smaller for the same mass, which translates into greater penetrating power and less aerodynamic drag. As it turns out, depending on how much (and in what) Tungsten-carbide powder (or simply "Carbide") is cemented or "matrixed" (usually in iron-nickel or cobalt), it has roughly the same mass advantage over lead as lead has over steel: at 14-18.5 gr/ccm density, some formulations are almost as dense as pure gold (19 gr/ccm). That sheer density makes the material VERY interesting from a ballistics standpoint ... in fact, if you run the numbers, a 3/8" ball of the stuff (roughly 36 cal or 9.5mm, which is comparable to "0000 Buckshot") can have roughly the same mass as .44 cal lead and 50 cal steel.

b} Hardness:

Tungsten Carbide is TOUGH stuff ... it's used on the tips of saw blades, for drill-bits, for shot-blasting the rust off of steel-plate, and the military uses it in high-velocity armor penetrators in certain anti-tank rounds, and also as the munition of choice in anti-personnel fragmentation munitions.

c) Non-Toxicity:

Unlike lead, which is a toxic heavy metal, carbide is relatively non-toxic.

d) Corrosion Resistance:

Carbide is naturally stable because the tungsten is already in a highly stable molecular bond with carbon, and is therefore resistant to corrosion in most ambient temperature conditions.

e) High Melting Point:

Tungsten has a very high melting point … so high, it was/is the chief ingredient in the filaments used in incandescent light bulbs.

Ok, so far, the stuff looks like a dream-material, from a munitions standpoint ... it's super-dense, extremely hard, corrosion resistant, and non-toxic. So why isn't everyone using it ? Therein lies the catch.

Disadvantages of Tungsten-Carbide:
(as a re-usable slingshot munition)

a) Expense:

Expense, expense, expense. This seems to be the biggie. First of all, this element is not as abundant as iron or lead, and it's very hardness and extremely high melting point make it difficult and energy intensive to work with … hence the expense. The chief use I've seen for most carbide balls seen on the internet are for super-hard long-life precision bearings in industry (and also for the tips of ballpoint pens), and they're expensive. There are small companies out there that have tried to market tungsten pellets as a non-toxic alternative to birdshot, but they've run afoul (pun intended) of the same price hurdle … hunters, even those who try to save money by loading their own rounds, don't want to pay upwards of $2-3 extra per shotgun shell, just to fire tungsten instead of lead or steel. It's even harder to find 0000 buckshot for deer.

b} Magnetism:

This is a relatively minor issue, compared to expense, but whether or not shot can be picked up with a magnet is either a yawner or a deal-breaker to some people, depending on the circumstances. For someone like me, who routinely reuses ammo, magnetically recoverable ammo is a big factor in determining whether or not something is cost effective. Tungsten-carbide by itself is non-magnetic. HOWEVER, most matrix formulations contain varying amounts of iron and/or cobalt … the more matrix, the more magnetic it tends to be. The drawback is that the more matrix is present, the lower the density falls in that highly attractive (pun intended) 14-18.5 gr/ccm range. In general, just looking at the chemistry, it's probably a safe bet that most carbide shot is going to be either weakly or moderately magnetic, if it lists at least 5-10% iron and/or cobalt as it's matrix.

Bottom Line: I'm assembling some cost data from several suppliers, with an eye towards unpolished 9.5mm size shot. Most of the sources I've found thus far are in China and India, but I found a source in California that's offering 9.5mm carbide balls for $38/lb, plus S&H, with a 1 pound minimum order, which seems like a viable source for a small test buy. I have several other potential; sources I haven't heard from yet.

The only way to know for sure how well suited this is for slingshotting is for me to get a small quantity, and shoot with it in my backstop/recovery setup. I'll post any progress I make to this thread.

Anyone else have any experience or data to offer ?

EDIT: to correct a mysterious posting error bug, I've had to strip out all formatting and hyperlinks from this post, which I'll try to restore as time permits.
 

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Ack ... kinda frustrating when forums auto-format a 'b'+')' into a
. It makes alphabetized lists looks silly, and for some reason I cant seem to edit the above post in this thread (potential bug). I usually set the auto-censor to auto replace it with 'b}' on my sites. Oh well.


Meanwhile, more data will be forthcoming, including a shot size/mass table, pricing, etc.

EDIT: Aaron - I sent you a debugging image. Please feel free to split this post over into the appropriate debugging area, if one exists.

EDIT2: I bypassed the bug by eliminating all special formatting and reposting ... now I can finesse it to restore the missing hyperlinks and fix the misalignments.
 
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Preliminary price data:

* Birdshot #5: Here's an outfit that sells tungsten birdshot #5 (too small for slingshot) at $24/lb. This formulation appears to be straight carbide, without cobalt, so it'd be non magnetic. {https://www.tungsten...6&code=TSS_SINK}

* BB & BBB sized shot: This outfit sells those sizes for just over $32/lb if you go for a 6lb min. That's steep, but if you're big into airguns, and cost is no concern, it might make for an interesting experiment to share with a few of your airgun friends: {http://www.tungsten-...gsten_shot.html}

* BALLS: The same outfit also sells larger size ball/pellets: 7.87mm, 8.2mm, 9.5mm and 12.7mm for $38/lb ($96/kg) plus shipping and handling {http://www.tungsten-.../inventory.html}. That's roughly 70 cents a shot for 9.5mm (3/8") or 35x the price of Royal Steel Ball's chromium slingshot ammo (2 cents each) and 2x the price of 4xx series stainless steel. If you have an effective backstop that captures virtually all of your ammo, then their one pound minimum order (roughly 50 shots of 9.5mm) becomes feasible to consider playing with. Their particular formulation appears to be maximum density 18.5 gr/cm**3, which is even closer to gold's density than the cobalt-matrix formulations I was referring to earlier, but accordingly it's probably low or non-magnetic. I have to admit, it'd be very cool to play with some 3/8" shot that has even greater range and penetrating power than .44 cal lead, and with the same mass as 50 cal steel.

I already have a call into that latter outfit, for samples ... people might want to hold off on calling in on their own until I have a chance to evaluate the stuff.

I also have a few queries with some other outfits I haven't listed yet.

WARNING/DISCLAIMER: Warning - although 9.5mm (3/8") is roughly the same size as 'quad-naught' (0000) Buckshot, I don't recommend putting the stuff in a shotgun shell without careful research, because it's so dense that the resulting compression could explode your barrel. Check your manufacturer's specs carefully before considering it. Ditto for people with airguns considering tungsten BB's ... check with your manufacturer. I can accept no responsibility for anyone but myself when it comes to playing with this stuff, so be sure to do your homework.
 

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Here's a quick comparison of a typical tungsten-carbide formulation, and how it compares to steel, lead and gold. This particular data is for a carbide-cobalt alloy #W273 (15% cobalt, rendering it slightly magnetic and electrically conductive).

Density:
Steel = 7.8 gr/ccm
Lead = 11.3 gr/ccm (+45%)
W273 carbide = 17 gr/ccm (+118%)
Gold = 19 gr/cm (+143%)

Ammo Mass, grams (Steel/Lead/W273):
1/4" = 1.05/1.52/2.28
3/8" = 3.46/5.34/7.555
7/16" = 5.6/9/12.21
1/2" = 8.37/12/18.23

Pretty dense stuff.
 

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ANOTHER WARNING (for gun users): because the carbide is probably harder than the material forming the barrel of your shotgun or airgun, use of carbide shot could, potentially, cause excessive wear, or scoring, of the inside of your barrel. Another reason to do any requisite specs homework before considering the use of this stuff.

I'm just looking at it from a slingshot perspective.
 

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ANOTHER WARNING (for gun users): because the carbide is probably harder than the material forming the barrel of your shotgun or airgun, use of carbide shot could, potentially, cause excessive wear, or scoring, of the inside of your barrel. Another reason to do any requisite specs homework before considering the use of this stuff.

I'm just looking at it from a slingshot perspective.
I would also like to buy some. I will wait for the responses.

Thanks for the information, Darb.
 

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Discussion Starter · #8 ·
Here are the sphere masses for tungsten alloy with a slightly higher density of 18.5:

Ammo Mass, gr (Steel/Lead/Tungsten):
1/4" = 1.05/1.52/2.48gr
3/8" = 3.46/5.34/8.22gr
7/16" = 5.6/9/13.28gr
1/2" = 8.37/12/19.83gr
 

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I'm bored and nothing is on TV, so it's time for a little light mathematical offroading.

I was considering impact force concentration just now ... just bear with me for a bit. Using basic geometric equations, I derived values for volume and hemispherical surface area (HSA) for the 3 most common standard size slingshot ammo already mentioned:

3/8" shot: Volume = 0.02712 CI, HSA = 0.22089 SqIn
7/16" shot, Volume = 0.043846 CI, HSA = 0.30066 SqIn
1/2" shot, Volume = 0.06545 CI, HSA = 0.392698 SqIn

Given that 3/8" tungsten, 7/16" lead and 1/2" steel are roughly the same mass, and if we then stipulate a situation in which all three shots are moving in parallel trajectories with the same approximate kinetic energy, we can then use their difference in HSA to approximate their difference in their ability to concentrate their impact force ... the latter would be approximately the inverse of the other (i.e., if A is half the size of B, it should have roughly twice the impact force concentration for the same kinetic energy). Thus:

* 3/8" tungsten has 73.37% of the hemispherical surface area of 7/16" lead, and therefore 36.3% greater impact force concentration. It has 56.25% of the HSA of 1/2" steel, and therefore 77.78% greater impact force concentration.

* The same approximate numbers probably hold true for comparing 7/16" tungsten to 1/2" lead to 9/16" steel.
 

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As a practical application, If looking only at the penetration, the 3/8 carbide is superior. The 3/8 carbide at long distances has a flatter trajectory and carries better because of the smaller size. But if delivering total energy to small game, the 7/16 lead is superior. It has sufficient penetration plus because of its softness, it does not tend to ricochet off and therefore delivers more dead blow and energy with most shots. The 1/2 steel is easier on a catch matt, therefore better suited for target shooting. At common slingshot shooting distances it is very hard to tell the difference in trajectory even though there is a little. Also the carbide is dog-gone expensive. -- Tex-Shooter
 

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Ah, some sagely direct experience from a true pro ... always better than mere theory and speculation. Thanks, Bill.


The tendency of hard shot to ricochet off hard bone at midrange and beyond hadn't occured to me ... but I think the non-toxicity advantage of carbide might help to mitigate that consideration for some.

Also (and this is just theory, not practical experience talking), if someone's shooting at something with bones strong enough to potentially deflect carbide, they should probably be using a gun or bow anyway ... for example, unless someone's an ace shooter who can reliably score head shots from med-range, I wouldn't recommend attempting a turkey with a slingshot, regardless of how strong your bands what ammo is used (turkey's, like squirrels, are very resilient for their size). I'd guess even canadian geese would probably be too big for slingshooting, unless someone's an ace head-shooter.

As for targets, I completely agree ... carbide is too expensive to use anywhere except in a backstop that allows reliable recovery and reuse. Stumpshooting, for example, would be a total waste of money.
 

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I have found that it is not just bone that defects hard shot such as carbide and steel! I have noticed that if hard shot is not close to the center of a targeted animal a lot of times it seems to slide off the hair rather than penetrate, but lead shot does not do this near as bad. I also have noticed that when hunting in a rocky area, hard shot will sometimes bounce right back at you. This is especially dangerous if hunting pigeons under a bridge. I don't recommend this anyway as it is illegal in some areas, but I know that it is being done. – Tex-Shooter
 

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...unless someone's an ace shooter who can reliably score head shots from med-range, I wouldn't recommend attempting a turkey with a slingshot, regardless of how strong your bands what ammo is used...
If attempting a turkey, squirrel or rabbit, a head shot is the only option.
 

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BTW, the high price of gold has apparently stimulated the use of Tungsten Carbide as a material for wedding rings. The selling point is that carbide, which is similar in weight to gold, is far harder ... the 2nd hardest substance behind diamond on the Mohs scale.

http://www.amazon.co...ref=pd_sim_jw_1

 

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I normally hunt for chicken with carefully folded paper money, rather than a slingshot ... but that's just me.
 

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^bump^

Just giving this thread a bump. I'm planning on placing an order for 1 lb of 3/8" tungsten sometime early next week. I was going to do it this week, but life has been ... busy ... and expensive, of late.
 

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You lost me, my friend ... I don't own a Tungsten ring. Mine's 14k gold.

I was just pointing out a recent trend in an alternate use of Tungsten.
 
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