In the book Guilty Pleasures, the first of the Anita Blake novels, Laurell K Hamilton had the heroine use that old werewolf trope, silver bullets. Silver bullets are almost a cliché in werewolf books, the noble metal which harms these nearly invulnerable lycanthropes. Got a troublesome 'were eating your friends? Just melt down that old silver dollar and Bam!, problem solved. So, Anita not only shoots silver bullets, she casts her own, just like all good werewolf hunters. However, silver bullets are not the easy solution they first appeared to be. It may not be impossible to make a working silver bullet, but it's far from an easy task. Since it's nice to have the books make sense, I figured I'd just go build some silver bullets, after all, how hard can it be? The Lone Ranger did it, right? However, before we continue with my efforts to produce a usable silver bullet, let me briefly discuss the history of silver, and how silver bullets came to be the de facto standard for werewolf extermination http://i128.photobucket.com/albums/p171/methosivanhoe/silver_bullets.jpg Silver History ============== Elemental (native) silver is quite rare in nature, it usually occurs in ores of other metals. Silver was therefore initially considered rarer and even more precious than gold. The first known efforts to mine silver occur in Anatolia, in present day Turkey. Egyptian gold ores contained a high percentage of silver, which they eventually learned to separate and refine, calling it "white gold". By about 2500 BC the Chaldeans found a means to purify silver from lead ores. This was a much more efficient means of obtaining silver, and greatly increased the amount of silver available in the ancient world. The Greeks discovered a large deposit of silver near Athens, which led to the famous Larium mines, which were worked for several hundred years. Silver proved to be a valuable metal; easily worked and durable. It was widely used for currency, art and medicine. Like gold, silver didn't rust or deteriorate. Naturally, their ability to resist tarnish, rust or canker caused both metals to be ascribed a variety of supernatural powers. The only other metal exhibiting this desirable property was platinum. However, platinum was so rare that prior to the eighteenth century it was virtually unknown in Europe. Silver isn't actually as inert as gold or platinum, and over time it will develop a blackish surface tarnish. However, prior to the industrial revolution, there was insufficient sulphur in the atmosphere to tarnish silver. Putative Supernatural and Magical Properties ============================================ In superstitious societies laden with religious overtones, silver came to be associated with various gods. It was obviously favoured by the gods, because they kept it bright and shiny. Silver also has strong antimicrobial properties which were recognized long before microbiology was even a glimmer in human consciousness. Wine stored in silver containers remained palatable longer than that stored in other vessels. Silver powders or tinctures applied to wounds prevented sepsis. Because some organic poisons contain high concentrations of sulphur, it was found that poisoned food or wine could blacken silver on contact, leading to the widespread custom of drinking from silver cups, or eating with silverware. Naturally, supernatural forces were used to explain these useful properties. Silver's highly reflective surface led to it being used for mirrors, and associated with the moon. Since women were also associated with the moon, over time silver was linked to everything female. It is a common component of magic, and used extensively in shamanistic and magical ritual, where it has been attributed with all manner of powers. In general, it's seen as a beneficial or benign substance, strengthening the effect of other magic’s, protecting and focusing the wearer, and reflecting or diffusing harmful energies. Magic Metal to Silver Bullet ============================ If one were looking for a magical weapon to kill a supernatural predator, particularly one with ties to the moon, silver is a natural choice. It was associated with powerful deities, the night, protection, healing and the supernatural in general. Besides, as every epic monster storyteller knows, the forging of the fatal weapon is one of the major points on the hero's journey. Silver was too rare and expensive (and soft) to be commonly used for weapons, so it added a little spice to the story if the hero had to procure one. The first generally-recognized silver bullet story comes from France. In the 1760's in the town of Gevaudan, a series of animal attacks left at least sixty people dead. Some estimates put the death toll over 100, but circumstances attending many of the deaths are ambiguous. There were numerous eye-witness reports of a large, highly aggressive animal who carried out these attacks, often seeking out human prey in preference to cattle or even sheep nearby. The creature became known as the "Beast of Gevuadan". The deaths were real, and well documented, but the creature responsible remains an enigma. Superstition and folk stories have become so thoroughly entwined that it is difficult to say what kind of beast it was, or even what it may have looked like. The local peasants were convinced that it was a werewolf (a loup-garou). Several people claimed to have shot or stabbed the monster, but without effect. In one account, two hunters shot it with rifles from close range, scoring multiple hits. The beast limped away, apparently hurt, only to reappear and kill a few days later. Professional hunters and trappers were dispatched with instructions to kill the beast. None were able to slay it, though several were apparently attacked and killed. Whole villages were abandoned when the beast was sighted nearby. Eventually, large groups of hunters and trackers, dogs and warriors were sent to search for the beast. Finally, one such group of men was attacked. Jean Chastel, a member of the group, had loaded a pistol with a silver bullet, with which he shot and killed the monster. The rest, as they say, is history. In myth, folklore and countless novels, the silver bullet (or arrow, or occasionally sword) is the sovereign cure for a rampaging lycanthrope. So, how hard can it be to come up with a functional silver bullet? I was pretty sure someone would be making silver bullets, and so I fired up my browser and went looking, assuming I'd just buy a box of them. I did find one company, BulletForge.com that claimed to make silver bullets. Sadly, their site stated that they had no silver bullets for sale, and were no longer accepting orders. Actually, that's just fine, because Laurell has already mentioned that Anita casts her own, and I need to figure out how to do it. I found that Popular Science had run an article on casting silver bullets. Apparently it wasn't impossible, as long as you have access to high-grade graphite, a well-stocked machine shop (and the expertise to use it) and a silver foundry. My bullet-casting experience is limited to casting a few wrinkled, imperfect musket balls using an iron mold and some lead we melted in a coffee can over the camp fire. It was obvious I was going to need professional assistance of the mold-making variety. After a bit of searching I found a custom mold maker with a sterling reputation, NEI Handtools Inc. So, I wrote them a nice letter, explaining that I was only partially crazy, and that I'd like to have them build me a graphite mold to cast silver bullets, in case I should ever be attacked by a rampaging werewolf. They were kind enough to put me in contact with Ed Wosika, a self-confessed gun nut and a veritable font of knowledge on all things ballistic. Ed and I exchanged emails... and more emails... and even more as I tried to rectify my nearly-complete ignorance of what it takes to make a bullet work correctly. Stability, the Greenhill formula, cross-sectional density, twist rates and rifling types were all foreign to me, and essential to making this project work. Thanks to Ed, I have a much better chance of making this work. Ed also mentioned an article in Gun World Magazine in which some ballistics buffs tried to recreate the silver bullets used by the Lone Ranger. He suggested I should get a copy of the article, which would at least allow me to avoid the pitfalls that they'd discovered. I contacted Gun World Magazine, and soon found myself conversing with the associate publisher, Viga Hall. He informed me that the company had changed ownership, and there no computer archives of past issues. He suggested that, since he was personally acquainted with several of the regular authors, if I could figure out who wrote the article in question, he would be willing to contact them and see what could be done. Back to the internet... after some searching I found what had to be a reference to the article in question -- and it listed an author, Jack Lewis. I wrote back to Viga, who informed me that he knew "Uncle Jack" well, and that Jack was still a regular contributor. Jack went out to his storage shed, and found an old copy of the magazine with the article, photocopied it, and sent the copies to Viga, who sent them on to me. The article was titled Lone Ranger Away, with the subtitle It's a Cinch Tonto Didn't Cast These Silver Bullets Over any Campfire. It details, in hilarious and witty dialog, the trials and difficulties some experienced gun experts had in casting silver bullets, and the extremely poor results they obtained when shooting them. MythBusters Silver and Lead Bullets =================================== At about this time I was informed that my favourite duo of television superheroes, Adam Savage and Jamie Hyneman, the MythBusters had done a segment on silver bullets. I've been a long-time fan of the series, but I had some complaints with this mini-episode. They cast a slightly-disreputable looking silver bullet, which was identified as being about 190 grains as opposed to 250 for the commercial bullet, and noticably smaller in diameter. They then loaded and tested the penetration of this silver bullet against a commercially-produced lead bullet. Not surprisingly, the lead bullet was the clear winner. I couldn't help thinking, however, that if they had pitted a high-performace silver bullet against an undersized lump of lead that the results might have been reversed. Curiouser and Curiouser ======================= The phrase "Silver Bullet" is a common idiom for the simple solution; the effortless resolution of a difficult problem. How curious that the namesake of the phrase should turn out to be anything but effortless. They weren't readily available, and by all accounts they weren't easy to make. Even more discouraging, even if silver bullets could be fabricated, the ballistic performance of silver bullets was so abysmal that their lethality was dubious. Casting a functional silver bullet is apparently not a task for the faint of heart. The idea that the average country boy, when faced with a killer werewolf, can run to his shop, bar the door, and quickly transform grandma's locket into a lethal bullet is looking very shaky. There must be a better way Shotguns ======== A shotgun presents a workable, quick and effective solution. In a normal rifle, the bullet fits the bore very tightly, and the expanding gasses evolved from the propellant accelerate it down the length of the barrel. A shotgun basically blasts a bunch of loose junk down the barrel. The bullets don't seal against the barrel, and after the initial explosion there's not much contained pressure. That's why shotgun barrels are so much thinner than rifle barrels. For the werewolf hunter, this presents several advantages. Most importantly, there's no need for the bullet to fit the bore. A moderately-skilled redneck could probably pry open a standard shotgun shell, dump out the shot, and stuff a chunk of silver chain, or even his class ring into the case. The resultant shell would almost certainly be functional, and at close range, deadly. If the hunter had a bit more time, it would be fairly easy to prepare silver shot in any size deemed appropriate. To make shot, a piece of steel screen is suspended over a tub of water. When molten silver (or another metal) is poured through the screen, droplets will form, surface tension will pull them into (more or less) spheres, which will harden when they hit the water. There's a real danger from steam burns and metal splatter, which may add spice to the story. Finally, shotshells are available for many popular pistol calibres. These are essentially shells loaded with shot rather than a conventional bullet. The shot is retained by a plastic cap, or by crimping the case. While the materials to reload these bullets are not commercially available (at least, not that I found), they could be very easily improvised. Pistols loaded with birdshot are going to be close-range weapons with fairly limited stopping power, but that actually makes for interesting story telling. Taurus is now producing a revolver capable of chambering .410 guage shotgun shells. The pistol is called the Judge. This would be a pretty stout pistol round, but it might be just what the intrepid werewolf hunter is looking for as long as you can handle the kickback... which is sure to be a bitch... Amalgam or Composite Bullets ============================ How pure does a silver bullet need to be? Does it need to be cast from pure silver, or is sterling good enough? What about 50% silver? There's no definitive answer to this problem, of course, but there's room for an author to play. If it's not critical that the bullet be of high purity silver, then an amalgam bullet may be a workable solution. So let’s say our protagonist is locked in the proverbial tool shed, with the hungry werewolf prowling outside. There's an old gas stove and a bullet mold sitting around. OK, that sounds unlikely, but in werewolf novels there's always a reloading bench in the shed, trust me on this. Our hero pulls some lead wheel weights off the classic mustang (also a de rigueur requirement for the shed), and fires up the gas stove to melt them. Then he pulls off his sterling silver class ring, and digs up a metal file, and begins filing the ring like a madman. The silver dust goes into the molten lead (which won't be nearly hot enough to melt the silver, thus producing an amalgam not an alloy), and the resultant slurry goes into the bullet mold. It's not pure silver, but the werewolf may still get a nasty surprise. Naturally, there are many variations on this theme. The silver can be any size from powder to bearings, as long it fits in the bullet mold. I'd be a bit scared to actually fire something like this. A bullet needs to be fairly strong to withstand the forces of firing, and these bullets might have a tendency to fragment . . . Sabot Rounds ============ A Sabot is a "wrapper" for a bullet that allows a smaller, lighter bullet to be fired from a higher caliber firearm. There are several types of sabos, but for our purposes the expanding cup is probably the most useful. Assuming we wanted to fire a 30-caliber bullet from a .44 caliber gun, we could get a plastic "cup" with a .30 calibre cavity and a .44 calibre diameter. When the projectile was fired, the plastic cup would fly down the barrel, engaging the rifling’s and spinning both it and the bullet it holds. As the assembly exits the barrel, wind resistance will cause the sabot to open up and fall off, leaving the bullet on course. Sabots are usually used to get a small bullet moving at very high speed, resulting in increased kinetic energy at short ranges. They're most commonly used with muzzle loaders, which otherwise have a tendency to lob huge chunks of lead at very low velocities, but sabos can and have been used with modern centerfire rifles. A sabot could be very useful for the itinerant werewolf hunter. Suppose the hunter casts a .30 calibre silver bullet in a conventional mould, making it from an old silver coin. As we'll see, this bullet will be several thousandths of an inch undersized and far too hard to shoot accurately. However, if the hero puts this in a sabot, suddenly neither the size difference nor the hardness is significant. Sadly, his friends may laugh at him for the funny-looking bullet, especially since sabots are usually made from brightly-colored plastic. Enduring the mockery of his friends will, one hopes, build character. CNC Lathe Turning ================= Shooters looking for super-accurate performance have found that solid bullets turned from rods of metal may offer better performance than cast bullets. There are a couple of companies making such bullets commercially (usually for big guns like the .50 BMG or the .338 Lapua). There is some debate on whether these bullets can be stabilized effectively by a standard barrel, and whether or not a driving ring’s are required to reduce the engraving pressures etc. However, it is certain that with some silver stock and a decent lathe a functional bullet could be produced. Unless the werewolf is to be dispatched at 1500 yards, the details of twist rates and bore diameter can be left to the hyper-accurate crowd. This would probably be a more practical method than casting bullets, as long as the protagonist has access to the equipment, the knowledge to use it, and some time on their hands. Silver Nitrate Bullets? ======================= Silver nitrate is a common silver salt that's been used as the photo reactive component of black-and-white film for many years. In its pure form it's a somewhat soft white solid which looks much like sugar. It's only about half as dense as pure silver, and not strong enough to make a functional bullet. Even if you could make a functional bullet, you'd still have problems. It's highly caustic, and is still used to remove warts and similar blemishes. Having a bullet that burns (and stains) your skin and corrodes your firearm is not ideal. It's highly toxic, and readily soluble, so you wouldn't want to eat one, or let them get damp. Silver Nitrate is also photo reactive - breaking down to metallic silver particles when exposed to light. In short, developing a workable bullet based on silver nitrate would be very difficult task. Not impossible, perhaps, but much more difficult that a normal silver bullet, and nothing I'm interested in pursuing. So where did this idea come from? The source of this particular myth was apparently a movie called Underworld. In the movie, werewolves are able to expel metallic silver bullets from their bodies. By these rules, getting shot with a silver slug isn't fun for a werewolf, but it's not fatal. The vampires, who are warring against the werewolves, develop silver nitrate bullets. Because silver nitrate is highly soluble, the bullet dissolves into the bloodstream carrying the silver throughout the body and killing the werewolf. The bullets are very pretty, with a silvery liquid that looks like mercury in a glass capsule. The werewolves, meanwhile, have a similar glass bullet filled with an "irradiated liquid" that glows a beautiful purple, and is lethal against vampires. The best thing that can be said about the silver nitrate bullets is that they were pretty. The movie's science is pretty shaky, but the special effects people earned their pay. Conclusion ========== There are several plausible ways of building a lethal silver weapon without the headaches associated with a cast bullet. However, nothing captures the imagination like the Van Helsing special: a traditional cartridge tipped with a gleaming silver bullet. Since Laurell already wrote that sort of bullet into the story, our quest lies in that direction. If we hope to succeed where others have failed, we're going to need to know a little bit about the silver, and what problems we face in using it as a material for cast bullets. The most obvious problem with silver is that it's not as dense as lead. Density is critical to bullet performance. The energy of a bullet after it leaves the barrel is directly related to its mass. Friction (air resistance) eats away at that energy, slowing the bullet as it goes down range. The ideal bullet, therefore, packs a lot of mass in a small volume -- which is the definition of density. A bit or research shows that while silver is less dense, the difference is only about 7.5%. Furthermore, the lead/tin alloys frequently used to cast bullets are also a few percent less dense than pure lead. Basically, if a silver is fairly 'long' it's cross-sectional density (mass per unit of frontal surface area) should be high enough to give very good ballistic performance. Melting Point Before you can pour metal in a mould, you have to melt it. As it turns out, lead melts at a relatively cool 621°F. You can melt lead in an old soup can over a camp fire. Silver, on the other hand, melts at a scorching 1761°F. Your campfire's going to need some help, and your soup can may not fare so well. Also, remember that chemical reactions (like oxidation) happen faster at higher temperatures. The need to flux, or possibly even create an inert atmosphere for the casting is much higher with silver than lead. There are a number of problems that can occur when pouring hot metal into a cold mould. With lead, the old timers just started pouring and figured that the first few rounds of bullets would be junk, but they'd warm the mould up enough for it to work well. Those first malformed bullets were just thrown back into the melting pot, and everything was good. The problem is that what you're really doing is bringing the mould up to a reasonable fraction of the temperature of the molten metal. Since silver's melting point is much higher, the mould needs to be considerably hotter. As a very rough rule of thumb, the mould should be at least a third of the molten material's temperature to perform well. Getting the mould up to 207°F for lead isn't too tough, but the silver mould needs to be nearly 600°F. Break out the hot-pads grandma, she's getting warm. More accurately, fire up a muffler furnace to pre-heat the mould, and handle it with tongs. Elastic Modulus =============== When a metal is plastically deformed (moulded like play dough), it tends to "rebound" a bit. The amount of rebound is different for different metals, and needs to be taken into account when building the moulds and dies. If a metal bar is extruded through a hole of exactly 0.5 inch, you won't actually get a 0.5 inch bar, you'll produce something a few thousandths of an inch bigger. Silver rebounds more than lead, in fact quite a bit more. One could make a sizing die that's a little smaller than one designed for lead bullets, mount it in a press that's been modified to handle the higher pressures needed to form silver, and get good results. However, that's a lot of money -- I'm going to try to accomplish the same thing by casting the bullet to the right size (or really, really close), and eliminating the need for the resizing die to do much of anything. Hardness ======== Actually, in metallurgy, there are several possible definitions of hardness. The one we're interested in is "Resistance of metal to plastic deformation". The harder the metal, the more energy is required to deform it. There are a number of ways to measure hardness, but most reloaders use the Brinell Hardness Number (BHN). Lead is a very soft metal, and has a BHN of 5, silver is much harder, with a BHN of 24.5. So why is hardness a problem? A bullet is expected to deform in response to pressure a couple of times. First, when the bullet is being loaded, it's run through a sizing die, which insures the bullet is no larger in diameter than it should be. If a cast lead bullet is a thousandth or two oversized, it's pretty easy to re-shape it. A silver bullet is going to take a lot more force, which may break the reloading press. More importantly, when a gun is fired a pressure wave slams into the bullet, deforming its base and sealing it against the bore. This process is called obturation, and is critical to accuracy. The rifling’s also etch into the bullet, and begin rotating it. With a silver bullet, the rifling’s are going to be a little harder to engrave, and the bullet isn't going to deform as easily. Even worse, a slightly oversize lead bullet will be extruded into the barrel when fired. It would consume some energy, so the bullet may not fly as far or as fast, but nobody's going to get hurt. A silver bullet might not be so accommodating, so we need to absolutely sure they don't exceed the bore diameter. All things being equal, harder bullets tend to consume more energy than soft ones, and show correspondingly lower muzzle velocities. In order to fire safely in an unmodified gun, and engage the rifling’s properly, a silver bullet needs to be fit to a much higher precision than a lead bullet. Hardness is not just a problem for silver, it's also a problem for standard bullets. While lead may be soft, many of the alloys commonly used are considerably harder. Hard lead ships better, and is better able to handle things like being loaded into a tubular magazine with a stiff spring. That's good news, because it means that reloaders already have experience in loading and shooting hard materials. In fact, some of the lead alloys being used are very nearly as hard as pure silver. Linotype, for example, is a commonly used "hard lead" alloy, with a BHN of 22. There are calculations showing the minimum pressure needed to properly obturate a bullet of a given hardness, and silver needs about 35,00 psi (242,000 kilopascals). Silver probably won't make a great choice for small-caliber pistols with lower chamber pressures, but for large-caliber hunting rifles this pressure is easily obtainable. By the way, these hardness numbers do dispell one common silver bullet myth. In many werewolf books, the hero or heroine melts down an old silver coin or piece of jewelry (usually with appropriate sentimental value) to make the bullet that ultimately kills the werewolf. Elemental silver has a BHN of 24.5, but is too soft for jewelry and coins. Those items are built from alloys engineered to make the silver harder and more durable, with typical BHN values between 100 and 150. A BHN of 100 would require chamber pressures of over 140,000 psi to obturate, which is far higher than any handheld firearm is designed for. So, old coins are out, we're working with pure silver! Thermal Expansion ================= Everyone who's ever used a thermometer knows that things expand when heated and shrink when cooled. Not too surprisingly, different materials expand and contract at different rates. When you pour a bullet, the material initially forms to the mould cavity then freezes when it drops below the melting point. At that point you have a hot bullet in the mould, which is going to shrink a little bit as it cools down to room temperature. The moulds are actually a cut couple of thousandths bigger than the desired bullet size, so that the cooled bullets work out to be the right size. Make sense? If I cast a Browning 9mil bullet from lead, I can calculate that I need to add about 2.4 thousands of an inch to compensate for the lead shrinking when it cools. Silver shrinks quite a bit more than lead. Both its melting point and it's coefficient of thermal expansion are higher. In fact, I'd need to add 11.7 thousands of an inch to the size of my mould cavity. And that, ladies and gentlemen, is why both the MythBusters and Jack Lewis noticed that the silver bullets were smaller than they should be. http://i128.photobucket.com/albums/p171/methosivanhoe/bad_results.jpg Summary ======= Here's what we learned from looking at the physical properties of silver: - Silver is dense enough to make an acceptable bullet. - Its high melting point requires better furnaces and technique than is needed for lead. - Silver coins and old jewellery are too hard, but pure silver (bullion) isn't much harder than commonly used bullets, and should work nicely. - For proper performance, a silver bullet needs to be cast to higher tolerances than lead - A standard bullet mould will cast a dramatically undersized bullet in silver, so a custom mould is needed. Casting silver bullets won't be as easy as I'd hoped, but I haven't found any reason why it can't work. If I manage to overcome the casting difficulties, it should be possible to get ballistic performance on par with hard lead bullets. And that's where this is heading. I was going to try to bodge things together with a couple of crucibles and some acetylene torches, in true redneck style. However, it had become obvious that, if this was going to work, I was going to need access to better facilities than my kitchen counter. So today I showed up in the Metallurgy labs, ready for our first attempt at casting silver bullets. The mould NEI sent me is in .45 calibre, and the bullets it casts are huge. However, we're not trying to get functional bullets yet. After all, we've calculated that the silver bullets out of a standard mould will be undersized. Our goal is to see if we can cast silver in a steel mould, and to determine how much smaller the silver bullets are than lead bullets cast from the same mould. Lead Bullets http://i128.photobucket.com/albums/p171/methosivanhoe/melting1.jpg When I arrived, Dr. Jaansalu had already started setting up equipment. We warmed the mould up to about 100°C and set up a Bunsen burner to melt the lead. Things went smoothly, and in short order we had molten lead and a hot mould. We assembled the mould, and held it together with a set of vice-grips, then poured the molten lead in. Given my virtually complete lack of experience with casting bullets, it worked surprisingly well. My pours were a little slow, resulting in some slight surface wrinkling in the bullets, but overall they looked pretty good. We cast four bullets, and called it good enough. http://i128.photobucket.com/albums/p171/methosivanhoe/shrinkage.jpg Silver Bullets ============== First we had to address the issue of preventing the silver from reacting with the steel mold. Remember, I was originally going to have the mold machined from graphite to prevent this problem. Dr. Jaansalu had originally suggested several complex mold-release agents, but he had a stroke of genius today. He suggested that we coat the interior of the mold with a very thin layer of carbon. I thought this sounded like a fine idea, but wasn't sure how we could achieve such a thing. Given my background, when someone says "thin layers" I start thinking about esoteric vacuum deposition chambers, which don't grow on trees. However, there is an easier way to apply a thin layer of carbon to a surface. The good doctor fired up a Bunsen burner, then shut down the oxygen supply. The result, naturally, was a fat yellow flame emitting lots of sooty... carbon. The mold sections were passed through the flame a few times, resulting in a nice, even (or at least even enough for our purposes) coating of carbon. This was cheaper than the vacuum chamber, and much faster! The question is, will this low tech approach work well enough to keep the cast bullets nice and shiny? Then we tried to melt the silver. Given it's high melting point, we were also concerned about oxidation. Dr. Jaansalu also informed me that molten silver has a tendency to absorb air, which not only hardens the metal but may cause it to spit, pop, and splatter when pouring. Getting splattered with molten silver doesn't sound like much fun. Rather than using a flux, he suggests that we rig a second Bunsen burner to create a reducing environment. I was delighted to have someone more knowledgable than myself making such decisions. The apparatus was very pretty. The main burner gave off the traditional bright blue flame, which turned magenta as it lapped around the ring stand and crucible. The brass diffuser of the upper burner gave its flame a bright green color. Overall, it looked like some fantastic olympic torch. With two burners running wide open, we placed five ounces of silver bullion in the cruicible, and waited. And waited. And waited. Despite it's considerable aesthetic appeal, this apparatus was unable to get hot enough to actually melt the silver. Plan "B" was to use a muffler furnace to melt the silver. We fired up the furnace, and went out for lunch while it warmed up. After lunch, we came back to a cold furnace -- the thermal alarm had tripped, and shut the unit down. After re-setting the alarm, we turned it up, and added the silver crucible. We also added a second crucible containing several graphite sticks, with the idea that the graphite would react with any free oxygen, preventing it from oxidizing the silver. We put the mold in a second furnace, and set it to 250°C, (482°F), trying to approximate the maximum temperature you might get by heating the mold in a kitchen oven. Ideally, the mold should be a bit hotter, but we're trying to avoid using too much equipment that Anita couldn't improvise easily. Finally, the moment of truth. We pulled the hot mold onto the refractory brick, and used a huge C-clamp to hold it tightly together. I pulled the crucible containing the molten silver, glowing a violent orange, and poured our first silver bullets. OK, I tried to pour silver bullets. The silver hardened on the sprue plate, and I was unable to actually fill the mold with silver. We heated up the silver, and tried again, with exactly the same results. Either the mold or the silver needs to be heated up more. We were very close to a successful cast. Sadly, our time was running out, and we decided to try it again next week. The results of our efforts: two partial silver bullets. Hoever, there is some good news. The carbon coating worked like a charm -- both bullets were bright and shiny, with no evidence of oxidation. The silver pour was smooth as glass, no spitting, popping or other nasty behaviors. If the silver had actually filled the mold it would have been a perfect pour. Our previous attempt to cast silver bullets was partially successful, but the silver cooled too quickly, and we weren't able to completely fill the mold. I was planning on just getting the mold hotter. Naturally, this would increase the rate of oxidation and the thermal expansion of the mold would add another variable to our efforts. Dr. Jaansalu suggested that we could just reduce the thermal conductivity of the sprue plate, preventing it from cooling the silver so quickly, and all would be good. Right. Reduce the what of the where? He explained his thoughts in small, simple words. Refractory materials have very low thermal conductivity. Metals are kind of the other end of the spectrum. If a layer of a thermally-resistant plaster was cast on top of the sprue plate, two things would happen. First, the sprue plate would be insulated, and cool much more slowly. Second, the silver would mostly contact the plaster, which acts as a thermal insulator. Overall, the silver should stay hot long enough to fill the mold. Well, sure it makes sense when he puts it that way. The good doctor prepared a batch of his special plaster. For those of you playing along at home, here's the recipe: 1. 15g Plaster of Paris 2. 5g Talc 3. 24 g Water The talc produces a very soft, easily damaged plaster that happens to be very heat-resistant. The sprue plate was covered with Vaseline as a releasing agent, and a bit of duct tape wrapped around it as a form, and the plaster was cast right on top of the plate. When the plaster dried, a hole and countersink was drilled to facilitate pouring the silver. Then the plaster was baked at 250°C, (482°F) for a few hours to desiccate it thoroughly. Having prepared a couple of plaster insulators, it was time to actually make a silver bullet. We melted the silver in exactly the same way as our previous attempt. About five ounces of silver were placed in the furnace, which was brought to 1100°C (2012°F). That's pretty warm, folks. When it was hot, we poured the silver bullets. This time the silver entered the mold easily, and I was able to fill it completely. My pouring technique still needs some help, but the equipment worked perfectly! In the photo to the left, you can see I'm just finishing pouring the second bullet. The sprue plate is covered by the plaster insulator, and small "buttons" of excess silver can be seen above the mould cavities. After allowing the silver to solidify, we moved the the next problem. The sprue plate is designed to pivot across the mold body, shearing across the base of the bullet and cutting the sprue (that bit of metal connecting the bullet to the pouring cavity). I've mentioned several times that silver is harder than lead. A quick tap with a mallet is all that's needed to cut the sprue on a lead bullet. Would the sprue-plate work with silver? A couple of sharp raps with the mallet, and we found the answer is clearly "Yes", although it takes considerably more effort. Enough extra effort that I suspect some maintenance may be necessary after every few silver bullets. Our first genuine silver bullets rolled onto the lab bench, and they looked great! We noticed a slight bit of pitting, and a hint of oxidation in the mold after this pour, and decided to try a different release agent. After spraying the mold with a bit of Boron Nitride, we set up for the second pour. This time the insulator was cracked. We pushed it all into place, and hoped it would serve well enough to complete the pour. When I poured the bullets, it shifted, and silver began to run over the side of the mold. I paused for a second (never a good thing when casting), then resumed pouring. The good news is that insulator held. The bad news is that my pausing had allowed the first part of the pour to partly solidify, resulting in a poorly cast bullet. The photo shows the two bullets from this pour still nestled in the mold. Notice the mold is a whitish-gray colour from the Boron Nitride. The voids in the base of the bullet on the right and the wrinkles in the bullet on the left are due to my poor casting. You can also see gaps at the top of the mold where the bullets have shrunk while cooling. Of Weights and Measures http://i128.photobucket.com/albums/p171/methosivanhoe/big_bullet.jpg So, we've got four silver bullets. Two of them are flawed, but two came out quite nicely. In this photo you can the lead bullets we cast last week arrayed behind our newly cast silver bullets. The purists will notice that not all of the bullets are perfectly smooth and lovely; a sad testament to my lack of casting experience. However, the silver bullets certainly look functional. So, we predicted that silver bullets should be a little lighter and smaller in diameter than their lead counterparts. With bullets of both types cast from the same mold, we're finally in a position to make the comparisons. The lead bullets weighed, on average, 35.13 grams (1.13 Troy ounces or 552.1 grains). The silver bullets averaged 30.52grams, but the last two bullets had obvious wrinkles and voids, which resulted in lighter weights. The first two bullets, which were better formed, were almost identical in weight and averaged 31.48 grams (1.01 Troy ounces or 484.8 grains). I measured the diameter of each bullet at the base, at two positions offset roughly 90°, and then averaged all readings. The lead bullets averaged .453 inches (1.151 cm), and the silver .448 inches (1.138 cm). http://i128.photobucket.com/albums/p171/methosivanhoe/lead_and_silver.jpg What Does it All Mean? ====================== Our experimental data confirms our previous calculations. Silver bullets are lighter than lead, but still sufficiently dense to achieve good ballistics performance. The diameter, however, is five thousandths of an inch too small. This, combined with the hardness of silver, would doubtless produce extremely lackluster performance were we to actually load and fire these bullets. However, we had never intended to fire these bullets. We should have enough information to design a mold to cast bullets for the Browning 9mil Anita was supposed to have used. Now... should i continue and actually try to cast a working 9mil bullet... M

Silver Bullets?