I’d stick with lead, It’s economical, easily shaped, cut, etc.
Handle with gloves, respirator when melting, sanding, etc. Minimum hazardous material exposure.
To quote Alfred E. Newman, “What? Me worry?” :smack:
Give the EPA a coronary! 
[hijack]
Q.E.D.
That is interesting about the half-life of Bismuth 209 (well at my age, it’s exciting 
)
On my website I have a time converter that spans a range of units from the Planck time all the way up to the half-life of Bismuth 209, the value of which I found was 2 × 10[sup]18[/sup] years. I think that value has been around for decades. Was that the theoretical value to which you referred?
Anyway, if the new value 1.9 × 10[sup]19[/sup] years is correct, I guess I’ll have to update that converter.
Not only that - think of the marketing potential of that new data:
Bismuth 209 - now with 95% less radioactvity!!!
:: Calling my broker right now to get a good price on Bismuth 209 futures. ::
[/hijack]
I’m a firm believer in industrial safety but I don’t think it’s necessary to go overboard.
Thousands of printers and Linotype operators handled tons of lead in type-metal (lead, tin and antimony) and breathed the fumes from the melted metal for many, many years. I would be interested in seeing life expectancy data showing that they suffered great harm. Ingested lead, such as in lead based paint, can be injurious to small children who tend to eat everything they touch. However adults aren’t growing and rapidly developing bone and such and their brains are fully developed and in fact are usually on a downhill curve.
Reasonable precautions: Don’t eat it. Don’t handle it all day and then lick your fingers, or drink the water you wash your hands in.
You can get osmium or iridium BBs at $31 and $16 per gram. Gold is currently about $18 per gram, and is easily available and workable. Tungsten is cheaper but unworkable. You can get it as small pellets or as fishing weights though. Tungsten used in shotgun shells is an alloy that is designed to bring it to near the same density as lead.
I’ve machined tungsten in a lathe. Drilled and tapped the ends and have the coolest darts in the bar.
Yes it’s very hard, but with the right tools it’s no worse than some of the alloys that have come through my shop. Unless you have access to a machine shop I’d say it would be very tough to do at home.
There was a place on the net that sold tungsten cylanders (tho at the time I was aware of them they were out of stock). They also sold magnesuim cylanders of the same size and someone used them as desktop items. Can’t find the place now though.
Brian
There was a model railroader who weighted N-scale locomotive bodies with depleted uranium to get more traction. This was back in the 70s or 80s, and I believe he worked for a defense contractor.
Iridium is rather inert; I’d go with that. Does anyone know if osmium metal will oxidize in air? The stinky tetroxide is some nasty stuff.
webelements says:
Note that the name “osmium” came from the “strong smell” of osmium compounds.
The tungsten fishing weights would be a cheaper way to go, and the OP might find some in the right size and shape for his purposes. Unless he has access to a machine shop like Mr. Goob’s, he’s not going to get them into any other shape. I’d love to see those darts, or, more specifically, pick one up. A commercial fabricator has this to say about tungsten:
Cool, thanks for the responses, all.
Anyone know where I can get 1oz chunks of Iridium? I’d be cool, just for the showoff factor, even if it didn’t end up being all the much smaller than a similarly heavy hunk of lead.
It appears to me (from this source )that the price of tungsten is around $3/ gram, and from here that the price of gold is about $18/gram. Since the two metals have density that is nearly equal, it would only take a bit of a denser matrial such as Iridium to make something with the density of gold. Then you gold plate it, (to some thickness… maybe a few mm) and you have yourself a pretty good counterfeit. How do people that buy bullion avoid getting taken like this?
Here. Enjoy!
It might have the same density, but the electromagnetic signature would be very different. This property is used to detect counterfeit gold bullion and coins, by using a purpose-designed metal detector. It works the same way as discriminating hobbyist metal detectors do to differentiate between valuable items, such as gold jewelry and coins, and buried junk, like tin cans and nails.
Here’s another source too: http://www.elementsales.com/
They will also cost you about $500 each
That was supposed to read “…could be used…” I don’t know for certain whether such a device is actually used for this purpose; there may be other methods that I’m not aware of. Paging samclem!
Even not considering this, a couple more points - I doubt that you can buy tungsten in ready made ingots formed to mimic gold bullion, appropriately stamped. You would face considerable expense getting the stuff formed into that shape, given the fabrication difficulties. Also, I suspect a lot of the protection for a gold buyer comes from a non-technical source. I doubt that gold bullion changes hands in any significant quantity without substantial identification and registration procedures. It would be difficult to cover your tracks well enough to prevent getting caught when somebody uncovered the deception.
BTW, if you follow the other links in this thread, $3/gram is very high. I suspect that is for extraordinary purity or specialized forms like wire or foil (your site is a research supply house). The guy selling the “pellets” on EBay is selling them for about $1/gram, and the 1/2 kg “desk weight” cylinders are priced at $99:
For those wondering why bismuth isn’t the densest stable element, there are two things which determine the density. First, there’s the masses of the individual atoms, and second, there’s how far apart the atoms are. How far apart the atoms are in turn depend on the size of the atoms and on the crystalline structure (some arrangements of atoms are more “efficient” than others). Although bismuth has a slightly higher atomic mass, it’s forms much less space-efficient crystals, so lead is still denser overall (and gold, tungsten, etc. are denser than lead).
Here’s a link to a thread from a few months ago about tungsten:
(I mentioned the fact it has almost the identical density as gold. I guess Q.E.D’s electronic detector would foil my plans for that … darn 
)
Slight hijack…
Can’t you shift some gear forward in the plane and get away from having to use any dead weight??
/slight hijack