Joined
·
784 Posts
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.
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.
