Always Make Sure of Your Ammunition Type

In the world of firearms, ammunition comes in several calibers (e.g. .22, .357, 7.62 mm, 9 mm, .45 etc.). However, when purchasing ammunition, one must be careful to specify the exact type of ammunition. We will see the reason why in this post.

Back when we studied rimfire cartridges, we noted that there are several cartridges in .22 caliber, such as .22 Short, .22 Long and .22 Long Rifle (i.e. .22LR). Besides these three, there are other cartridges too, such as .22 Remington Jet, .22 Reed Express, .22 CB etc. Most of these, except the last one have .223 inch diameter bullets, but the length of the cartridges and the bullets differ. Therefore, if a firearm takes (say) .22 Long cartridges, the user will never be able to fit a .22 LR cartridge into the chamber.

The same thing is true with other calibers as well. For example, we have .380 vs. .38 S&W vs. .38 Special vs. .38 Short Colt vs. .38 Long Colt. In mathematics, we are taught that 0.380 = 0.38, but when it comes to cartridge sizes, they are two completely different things, as the image below shows:

.38 Special (left) vs. .380 (right)

Not only are the lengths and cartridge profiles dramatically different, the two bullets are also slightly different diameters as well: .38 special has a .357 inch diameter bullet, whereas .380 has a .355 inch diameter bullet.

Similarly, when referring to .45 caliber ammunition, it should be specified if the user wants .45 ACP, .45 GAP, .45 Webley etc. As before, all of these have dramatically different cartridge shapes and bullet weights.

.45 GAP (left) vs. .45 ACP (right)

As before, the reader may observe the difference in the sizes and shapes of the cartridges. Incidentally, ACP stands for Automatic Colt Pistol and GAP stands for Glock Automatic Pistol, the names of the manufacturers whose products these cartridges were originally designed for.

Finally, we have many cartridges in 7.62 mm: 7.62x25 mm. Tokarev, 7.62x51 mm. NATO, 7.62x39 mm. Soviet, 7.62x54 mmR etc. The two most famous ones are the 7.62 NATO (i.e. 7.62x51 mm. used by FN-FAL, M14, Heckler & Koch G3 etc.) and the 7.62 Soviet (i.e. 7.62x39 mm. used by the AK-47, AKM and Type 56 rifles).

NATO 7.62x51 mm. (top) vs. Soviet 7.62x39 mm. (bottom)

As the reader may note, it is pretty easy to tell that the two cartridges are drastically different.

The same thing applies to many other calibers as well. So, the buyer must note the exact cartridge type when purchasing new ammunition. As amazing as it may seem, quite a few people are not aware of the differences between the cartridges or that the other cartridges exist. There have been several instances where a buyer has walked into a local firearm store and asked for .38 cartridges and ended up walking out with either .38 S&W or .38 Special, when they really wanted .380 cartridges, or asked for .22 Long when they really wanted .22 Long Rifle etc. It is a source of frustration to both the buyer as well as the owner of the firearms shop.

Therefore, it is very important to note down the exact type of cartridge that a firearm accepts.

What is a Boolit?

The term "boolit" may be seen on some forums on the internet these days. Well, what is it, the reader wonders? Well, wonder no more.

The word "boolit" is a made-up word and is not part of the English language. It is a deliberate misspelling of the word "bullet". The origin of this term seems to have come from a forum called castboolits.gunloads.com and spread from there on to many other shooting forums (mostly those with a lot of American members). As per the forum, a boolit is a projectile that is hand cast by a person for use by an individual, whereas a bullet is a machine-made projectile made by a commercial company for mass consumption. Another common difference per the forum members is that a "boolit" is cast from a mold, whereas a "bullet" is a jacketed projectile.

In the good old days, many fire arms came with their own bullet molds.

Some enthusiasts like to make their own bullets, just the same way that their forefathers used to. And quite a few of them refer to their own custom made products as "boolits".

Self Lubricating Bullets

Your humble editor recently came across an interesting book called "Modern American Pistols and Revolvers". The book dates from 1896 and describes the state of firearms that was considered "modern" in that era. Among its many pages was a mention of something called a self-lubricating bullet.

Self-lubricating bullets seem to have been invented by Daniel B. Wesson, one of the founders of Smith & Wesson. He received a patent for his design in 1893. During this era, fouling in firearms was a big problem because smokeless powders hadn't been invented yet and black powder left a lot residue behind in the barrel. Excessive fouling would cause the finest revolvers in the world to become inaccurate, especially when they were shot rapidly in dry conditions.

Smith & Wesson self lubricating bullet. Click on image to enlarge. Public domain image

In the above image, we see a Smith & Wesson self-lubricating bullet. The bullet has a hollow core in its base, about 1/8th inch in diameter. Inside this core, a copper plug is inserted and the core is filled with lubricant A. The base of the core has a brass plug B. Four tiny passages C are drilled along the side of the bullet and these passages are also filled with lubricant.

Self-lubricating bullet when fired. Click on image to enlarge. Public domain image.

When the bullet is fired, the brass plug B is pushed inside the bullet by the expanding gases, thereby forcing out the lubricant out of the passages C in the conical front of the bullet. The theory was that the lubricant would distribute itself to the walls of the barrel and keep it moist. The black powder residue, which is very hot, would cool down more rapidly because of the lubricant and adhere only loosely to the barrel and could be cleaned easily with only a wire brush.

The book goes on to say that this cartridge was tested by the US Government and seemed to show more accuracy than using regular ammunition, while being slightly more expensive. Smith & Wesson used this idea for several of their cartridges, .38 S&W, .38 Special, .32 S&W, .32 S&W Long, .44 S&W Russian etc.

With the invention of more modern and cleaner burning powders, this type of bullet seems to have lost its popularity.

What's the deal with teflon coated bullets?

During the early 1980s, there was quite a bit of controversy about teflon-coated bullets. Some news articles even went so far as to label them as "cop killers". The reader is probably thinking at this point, "Teflon? Isn't that the stuff that they coat non-stick cooking pans with? Why is that so dangerous?" This article aims to clear up the mystery.

Teflon coated bullet

Our story starts in the 1960s, when a company called KTW Inc. (named after the founders last names, Kopsch, Turcos and Ward) from Ohio was trying to develop a bullet with better penetration characteristics. Common handgun bullets which were largely made of lead, had the problem of deforming upon hitting a hard surface, such as a car door or a windshield, and became less effective after they deformed. KTW was trying to invent a better bullet for use by police departments (in fact, one of the founders, Daniel Turcos, was a police sergeant at that time and the other two founders worked in the coroner's office of the Ohio police department).

They eventually settled on a bullet design that consisted of a steel core, with an outer jacket made of hardened brass. This bullet offered much better penetration than older lead bullets, but it had a problem because of the hardened brass layer on the outside of the bullet. This hard layer did not engage the handgun's rifling very well and the friction caused the barrels to wear out prematurely. To reduce the barrel wear, the inventors coated the outside of the bullets with teflon, because teflon is very slippery and is one of the best lubricating substances known to man (the same reasons why teflon is used to coat the surfaces of non-stick pots and pans).

In 1982, NBC ran a special television report on these bullets where they argued that these bullets were a danger to police officers (many police departments had requested NBC not to run that program). After that television show, many American gun-control groups started to call these bullets as "cop killers" because they could penetrate the ballistic vests that many policemen used to wear at that time. Unfortunately, many of these reports wrongly reported that the teflon coating was the reason that these bullets had better penetration, rather than the hardened brass jacket which was the real reason. Movies and TV shows continued to spread the myth that coating ordinary bullets with teflon suddenly made them capable of piercing armor plates.

Because of the publicity, North Carolina, South Carolina, Oregon and Oklahoma have laws that make it illegal to possess teflon coated bullets, while Virginia makes it illegal to use teflon coated bullets to commit a crime.

KTW stopped producing these bullets in the 1990s and they're not encountered as much these days. However, there are other manufacturers who coat their bullets with other lubricating substances, such as molybdenum disulfide, wax, lubalox etc.

Bullets: Modern Bullets - II

In our last post, we looked at advances in bullet technology from the 1900s onwards. We also studied some modern bullet types. Now we will study some more modern bullet types.

The first type of modern bullet we will study is the "boat-tail" bullet. This type was invented in 1898 in France, as an improved spitzer type bullet (which we studied in the last section). The problem was that as bullets speeds started to increase, it was found that as a bullet moves in the air, the resulting vacuum created by its motion slows down the tail end of the bullet. It was found that by tapering the back of the bullet, the drag caused by the vacuum was very much reduced. The improved bullet was called Balle D by the French and the design was soon copied by other countries.

Note the typical taper at the back of the bullet that characterizes a boat-tail bullet. Above 400 yards or so, boat tail bullets come on their own and show much more improved performance over normal spitzer bullets. Many high powered bullets these days are boat-tails.

The next type of bullet we will study is the tracer bullet. These bullets were originally introduced by the British for use with the venerable .303 rifle in 1915. The base of a bullet of this type is hollow and contains some pyrotechnic material, such as phosphorus, strontium compounds, barium compounds, magnesium etc. When the bullet is fired, these compounds ignite and leave a visible trail along the path of the bullet. This allows the shooter to see where the bullets are ending up. Since the tracer chemicals burn as the bullet flies in the air, the bullet loses mass as it travels. Hence, a tracer bullet must be spun at a higher rate of spin than a normal bullet in order to maintain stability in the air. Also because of the loss of mass, the tracer bullet often hits at a somewhat different location from where a normal bullet would go.

There are a few types of tracer ammunition. The oldest type is the bright tracer, which starts burning the moment the bullet leaves the barrel, and burns very brightly. However, this trail is visible to everyone around and thus gives away the position of the shooter as well. These types also tend to overwhelm night vision devices with their bright glow. Newer types of tracers attempt to fix this issue. Subdued tracers have a delayed startup and only burn brightly after the bullet has traveled past about 100 meters or so. This way, it does not give away the shooter's position. Yet another type of tracer bullet called the "Dim Tracer" does not produce much of a trail since it mostly emits infrared light. It is intended to be used along with night vision equipment. Another new development in tracer technology uses an LED instead of chemicals, so it is only visible from the position of the shooter. This also has the advantage that the tracer does not lose mass as it travels and hence stays more accurate. US forces generally tend to load their ammunition so that every 5th bullet is a tracer bullet.

The next bullet type is the armor piercing type. Basically, this looks similar to the jacketed bullets we studied in the previous post, but the tip is made of a harder material such as tungsten carbide, steel, depleted uranium etc.

Another type of bullet is the flechette bullet. Basically these bullets have vanes in the back, similar to feathers at the back of an arrow. These vanes serve to keep the bullet steady in the air, so there is no need to spin the bullet with rifling. Some shotguns firing flechette bullets were introduced in Vietnam and there is still research this field today.

Bullets: Modern Bullets - I

In our last post, we saw how spherical balls were gradually starting to be replaced by elongated bullets, especially since it was determined that elongated bullets could be given more accuracy than spherical bullets, if they were spun about their axis by rifling. Now we will study the development of modern bullets.

Recall that in our discussion about the early bullets, we noted that they were mainly made out of pure lead because the material is easy to shape, cheap, readily available and extremely dense. The problem with lead is that it is also very soft and melts easily. Lead balls performed satisfactorily for a few centuries when gunpowder was low quality and velocities of the bullet were not that high. However, as the gunpowder quality and power began to improve and as the bullets began to fit the gun barrel more tightly, the velocity of the bullet began to increase and the pressure and temperature in the barrel was also higher. The temperature of the bullet would rise not only because of the hotter burning gunpowder, but also due to the friction generated by rubbing against the barrel. This meant that the lead bullet had a good chance to melt and deform due to the extra temperature and pressure. This would cause the bullet to leave a good bit of lead behind inside the barrel and it would have to be cleaned often. The deformation of the bullet would also cause a loss of accuracy.

One solution that we've already seen when discussing the manufacture of shotgun pellets earlier, is to add a bit of antimony to the lead. This increases the hardness of the lead alloy and makes it resist higher pressures.

However, adding antimony did not solve matters much, especially after more powerful gunpowders such as cordite came out. The bullet would be stripped due to the rifling and the lead would deposit on the inside of the grooves, making the weapon useless very quickly.

The next solution was invented by Lt. Colonel Eduard Rubin at the Swiss Federal Ammunition Factory and Research Center in Thun, Switzerland in 1889. His solution was to make a thin outer layer of copper which would be filled on the inside with lead. Since copper melts at a higher temperature than lead, is harder than pure lead and has a specific heat capacity higher than lead, the outer layer prevents the bullet from getting deformed too much. The inner layer of lead adds to the weight of the bullet. Such a bullet is called a jacketed bullet. The jacket may extend throughout the front and sides of the bullet, in which case it is called a full-metal jacket (FMJ), or it may only extend around the parts that fit tightly around the barrel and the tip may be of softer material, in which case it is called a soft-point bullet.

Note that the jacket is not always made of copper these days. Cupro-nickel and other copper alloys, steel and gilding metal are all commonly used these days. Nylon and other synthetic materials were also tried out without much success.

Note that a pure lead bullet expands on striking the target because the lead in the back mushes the lead at the front of the bullet and thereby causes much more damage to the target after it expands. A full-metal jacket bullet does not expand much on striking the target, because of the jacket constraining the target, hence there is generally less tissue damage. On the other hand, the harder jacket allows it to penetrate further into the target. One way to counteract the lack of expansion is to unbalance the bullet (make it heavier at the back) so that when it hits the target, it yaws in different directions as it penetrates the target. This is done by making the front of the bullet of lighter material, such as aluminium instead of lead.

A soft-point bullet expands when it strikes the target, since the front of the bullet is a softer material. Hence it generally causes more tissue damage than a full metal jacket bullet. However this expansion is limited by the outer jacket as well.

Another solution is to make the jacket cover the entire bullet, but make the tip of the bullet hollow, so that it expands when it hits the target. These bullets are called hollow point bullets or Jacketed Hollow Point (JHP). They were first manufactured in 1890 in a factory in Dum Dum, West Bengal, India and hence these bullets are also known as "dum dums." These bullets were quickly outlawed for military use by 1899, but they can be used by civilians and are used by hunters in many parts of the world.

GFDL licensed image from wikipedia.com

The above illustration shows three modern cartridges. Note how tapered these bullets are. The one on the left of the picture is a hollow point, as can be seen by the hollowed out shape at the tip. The bullet in the middle is a full metal jacket bullet. The one on the right is a soft-point bullet. Notice the tip of the soft-point is of a different color than the rest of the bullet, because it is a different metal.

As you may have noted above, the bullets of the three cartridges are extremely pointed This innovation in bullet design came from the French in 1898 for their Lebel 8 mm. rifle. They made the tips of their bullets more pointed, to improve the aerodynamic characteristics of the bullet and increase its range. Shortly after, the Germans copied the same idea in 1905 and called their bullets Spitzgeschoss or "pointed bullet". This gave rise to the term spitzer bullet, which is the generic English term for any bullet with a pointed tip. This concept was rapidly adopted through-out the world and now, virtually every country uses spitzer type bullets for rifles.

GFDL licensed image from wikipedia.com

In the above image we see two types of cartridges. The one on the left is a rifle cartridge that operates at higher velocities and hence it has a spitzer-type pointed bullet. The one on the right is a pistol cartridge. As you can see, it is a shorter cartridge and has a bullet with a rounded tip. This shape does not offer as much range or penetration as a spitzer-type bullet, but it is optimized for reliable feeding in an automatic pistol.

Bullets: Conical Expanding Bullets

In the 1800s, many people began to realize the advantages of rifling and started to make weapons that included rifled barrels. The problems associated with rifling were that if a bullet was too large, it would be difficult to insert it into a rifle and if it was too small, the gases would escape around the bullet and decrease its range.

The first breakthrough was by one Captain Norton who was stationed in India in the 1830s, who invented the first expanding bullet. He was followed in 1836 by Mr. William Greener, a well known Birmingham based gun-maker, who invented a compound bullet that could expand as it was fired. The British authorities paid little attention to their inventions and one of the reasons they rejected these bullets was because they were not spherical balls

In 1849, a Frenchman named Minie took the same idea and made a compound bullet called the Minie ball. We discussed all these three inventions earlier and the reader is invited to go back to that article and observe the pictures of the various bullets.

These were among the first conical shaped bullets that were used. Until then, the bullets were usually shaped as balls. A few years later, Mr. Joseph Whitworth, the pre-eminent mechanical engineer of his day was contracted to improve the rifle and he realized the value of elongating the bullet. The result was a new rifle that used polygonal bore and an elongated polygonal bullet to go with it:

We've also discussed the whitworth bullet in some detail in an earlier article and hence, we will not repeat that discussion here, other than to mention that these new bullets guaranteed better accuracy than the older spherical bullets. As a result of this, spherical bullets went out of fashion and the modern elongated bullet slowly started to gain in popularity.

Bullets: Swaging

In our last post, we saw how smaller shotgun pellets are made. Pellets larger than 6 mm. cannot be made by this technique though and have to be made either by casting, or by using another method called swaging. We will study swaging in this post. Note that swaging is not used only for larger shotgun bullets, but also for making bullets in general. It can be used for making solid bullets, compound bullets, jacketed bullets, hollow point bullets, lead bullets, plastic bullets etc. Most major ammunition manufacturers use swaging techniques for making bullets today. It is ideally suited towards high-volume manufacturing, with very little variation between all the bullets made this process.

So what is this swaging process? It is generally a cold-formed forging process (i.e.) the work is usually done at room temperature, without heating the metal. It consists of a hard metal die which has a cavity of the desired shape of the bullet inside it. Lead or any other material is inserted into the die's cavity and then it is put under pressure by means of a metal punch which is forced into the die under pressure until it reaches a preset depth. The punch pushes the lead material (or other bullet material) into the shape of the cavity. The pressure to the punch may be applied by a manual press, a hydraulic press, repeated hammer blows, or by using a threaded punch that is screwed on. For most industrial-style manufacturing, a hydraulic press is used and the pressure applied is in the range of a few tons. The pressure applied depends on the hardness of the bullet material, its ductility, shape of the bullet etc. After the bullet material has been shaped, the punch is then removed from the die, the die is opened and the swaged item is removed. This process allows for uniform density and repeatability of process with very high accuracy.

If a bullet made of multiple materials is desired (e.g. a jacketed bullet, tungsten tipped bullet or a tracer bullet), then it can be done in multiple swaging steps, i.e. insert the first material into the die and apply a punch to make the first layer, then insert more materials and then apply the punch again for the second layer and so on.

This technique has several advantages over casting bullets. In casting, since the molten metal shrinks when it solidifies, the mold must be slightly larger than the desired size. Therefore it is harder to control the size of the final product. Since swaging happens at room temperature, the swaging die is the exact size of the bullet desired and therefore produces a more accurate-sized bullet. Swaging can be used to make compound bullets and jacketed bullets made of multiple materials, whereas casting can make bullets that are only composed of one material. Cast bullets may have defects such as air bubbles and cracks, whereas swaged bullets do not have these defects. Swaging can also be used to make non-metallic bullets, such as plastic bullets.

Bullets: Shotgun Pellets

In our last post, we saw how lead balls were made by casting lead in a mold to form spherical bullets. The lead balls were used, one per shot, so the methods described in the previous post were used to manufacture them.

In the case of shotguns, different types of cartridges are used. In some cases, these contain a single large ball, in which case the previous methods of manufacture were used. However, certain types of shotgun cartridges use dozens of small spherical pellets instead of a single lead ball. In this case, manufacturing these small pellets using the casting techniques from the previous post is simply not practical. Instead, a different technique is used to manufacture these pellets. This technique is usually used to manufacture pellets up to 6 mm. in diameter or so, as it is not suitable for larger diameters.

We will first study the historical technique, which was invented in Bristol by one William Watts in 1782. The process starts by acquiring a location where lead may be dropped from a height of 40-60 meters. This could be a tower on the ground (called a shot tower), or an old mineshaft. In William Watts' case, he had a natural cave running under his house, so he built a three story tower and then dug a shaft in the ground till he hit the caves. There is a furnace at the top where lead can be melted. The molten lead is poured into a pan that has holes in the bottom of it, corresponding to the diameter of the pellets desired. The molten lead slowly percolates through these holes and forms globules which fall down to the bottom of the tower or mine shaft. During their fall, the molten lead globules become spherical shaped, much the same way as raindrops form spheres as they are falling so that surface tension is minimized. During their fall, the globules also harden in the air. At the bottom of the shot tower or mine shaft is a container filled with water. The fall through the air must be long enough for the pellets to harden sufficiently before they contact the water container, otherwise they will be flattened on impact. Typically, the pellets are dropped from a height of 40-60 meters for this to happen, though some shot towers are even taller. For instance, the Phoenix shot tower in Baltimore, MD, was the tallest building in the US at 234.25 feet (71 meters), when it was first built in 1828. The lead must not contain any zinc impurities and must have a small amount of arsenic in it, in order for the globules to form properly.

The more modern technique is the Bliemiester method invented by Louis A. Bliemiester of Los Angeles, CA and has been in use in the US since 1959. In this method, molten lead is dropped for a short distance of about 1 inch (approx. 25 mm.) into a container of very hot water. The pellets then roll down an underwater incline and then drop another 3 feet (approx. 1 meter). The hot water controls the rate that the lead pellets cool and harden and the surface tension ensures that the pellets are spherical. This method does not require a tall shot tower to be built and hence is the preferred method these days, while shot towers are now largely historical landmarks.

After the lead has cooled down, the shot pellets are gathered from the water container and classified into different shot sizes and any imperfectly shaped ones are removed and remelted. In the Victorian era, this was done manually by women who would gather the pellets in their aprons, dry them and judge whether each pellet was properly formed on not, by looking at them. The modern process is automated and is consequently faster. In the modern process, the shot pellets are taken out of the water container and put into a steam-jacketed tumbling barrel, where they are dried and polished. Next, they are taken to grading tables. These grading tables are located on an inclined slope and consist of a series of "steps" with gaps in between them. Each step is slightly lower than the previous one. The shot pellets are allowed to roll down the tables. Pellets that are sufficiently spherical shaped will jump across the gaps between the steps. Pellets that are improperly shaped or have multiple pellets fused into one, will not jump the gaps and will fall through into scrap boxes. The bad pellets are collected from the scrap boxes and remelted. The good pellets are taken through a series of vibrating mesh screens, each of which have a mesh of a particular size. The mesh screens sort out the pellets into standardized sizes, by keeping pellets above a certain size on top of the mesh, while allowing smaller sized pellets to drop through them. These sorted pellets are then packed into bags and shipped out to a cartridge manufacturer.

If the pellets made with this technique are made of pure lead, then they are known as drop shot. If a small amount of antimony is added to the lead, then these pellets are known as chilled shot. Pure lead pellets are somewhat softer and thus they get deformed more when fired with more powerful cartridges. Addition of antimony to the lead makes it an alloy that is a bit harder and can withstand higher pressures.

As mentioned before, this technique can only be used for smaller diameters (less than 6 mm. or so) and larger shot must be manufactured using casting or swaging techniques. We have already studied casting in the previous post and we will study swaging in the next post.

The sorted pellets are used by cartridge manufacturers or home reloaders to manufacture cartridges.

Bullets: Early Bullets

In the early days of firearms, bullets were mostly made of cast lead balls. When we look at early firearms such as the petronel, culverin and matchlock weapons like the arquebus, these were essentially hand made weapons and the user was often the same person who helped build it. None of these weapons were built to any particular standard and hence, each weapon was supplied with its own bullet mold, so that the user could cast their own bullets as needed. Even when weapons like the caliver (which was built with a standard bore size and gave us the English word "caliber") were introduced, users were often supplied a set of bullet molds with them.

What we have here is an antique musket's bullet mold. This type of mold is called a scissors mold and is made of cast iron. The specimen is a bit pitted due to wear and tear, but still works very well when it comes to casting bullets. It looks similar to a pair of pliers, except that the jaws enclose a hollow spherical section in between them. The picture below shows the view of the other side of this mold.

As can be seen from the above picture, the two scissor arms can be manipulated to open or close the mold as needed. The picture below shows how the mold looks from the inside, when the jaws are opened.

To cast a ball, the user initially melts a quantity of lead in a container. Then the user closes the mold and pours in some lead through the hole on top. The lead quickly cools and solidifies inside the mold. Next, the user opens the jaws by manipulating the scissor arms and extracts the bullet. This bullet is mostly spherical except for a tiny bit of projecting metal, called the sprue which is formed by lead hardening in the hole through which the lead was poured through. There is usually a thin parting line formed around the ball as well, along the line where the mold opens. The lead bullet is taken out and then the sprue and parting lines are filed off, to leave behind a spherical bullet.

Of course, using a mold like this is slower work, since the user can only produce one bullet at a time. It must be said that lead does solidify fairly quickly, but this is a slow process even then. A faster way to handle this is a multi-bullet mold, something like the example shown below:

In the diagram above, we see a design plan of a hinge-type bullet mold. In this one, the jaws are closed and molten lead is poured down the groove in the middle of the jaws. After the lead cools, the jaws are opened to reveal four bullets which can be cut free from the sprues and then filed down to spheres. The left over lead from the casting can be remelted for the next batch.

The picture above shows a multi-bullet mold used for the famous Brown Bess musket, which served British forces for over one hundred years. This particular mold is made of soapstone and comes in two halves. Note the two wooden pins sticking out of the center of one half of the mold and the two corresponding holes in the middle of the second half. These pins are used to make sure that the two halves of the mold are properly centered. The two halves of the mold are brought together and then molten lead is poured through the holes along the edges. After the lead is allowed to cool, the two halves of the mold are separated and eight musket balls are taken out. As before, the balls are mostly spherical, but they have a little extra projection where the lead has cooled at the holes through which the lead is poured in. There is usually also a little thin parting line around the circumference of the ball corresponding to the two halves of the mold. These projections must be filed out and then the balls are ready to use.

It must be remembered that there are a few issues with metal casting. For one, the molten metal must be poured into the mold slowly, so that the air inside the mold is allowed to escape, otherwise the cast bullet may have air bubbles trapped inside it. Also, molten metal occupies a bit more volume than solid metal, so the casting shrinks a bit when it solidifies. Hence, the final casting is a bit smaller than the mold itself.

As these balls were mostly used with muzzle-loaders, the size of the ball was generally a bit smaller than the diameter of the musket bore, so that these were easy to load into the firearm. For example, a Brown Bess musket's bore was 0.75 inches, so the balls produced by this mold would be something like 0.69-0.70 inches in diameter. The user would first pour some gunpowder down the barrel, then take a ball and wrap it around a greased patch to provide lubrication and a tighter fit and then ram the resulting package into the barrel.

Spherical lead balls were in use for a very long time between the 1200s and 1800s or so and it was not until the 1820s that people started to slowly go for other types of bullets. These bullets are still used today by certain hunters who wish to hunt like their ancestors did.

Bullets: Basics

After reading up about different types of propellants, we will now study the history of bullets. It may come as a surprise to some people to realize that the history of bullets predates the history of firearms. Bullets have been found in some of the ancient ruins around the planet. These bullets were not fired from firearms, but were fired from slings and handheld catapults. Some of these bullets were made of stone, others were made of metal.

The word "bullet" derives from the French word, boullet, which means "little ball". A lot of the early bullets were spherical balls and it wasn't until the 1820s or so when the bullets started to change shape.

When it comes to bullets for firearms, one thing is common to all of them, whether they were made in the 1200s or in the 2000s. A majority of them have a large percentage of lead. There are a few good reasons why this is the case.

In order to be a good bullet making material, the following characteristics are desirable:

1. Density: The bullet must be made of dense material so it can pack as much mass as possible in a given volume.
2. Low cost
3. Easy to shape
4. Availability of materials.

Lead seems to fit all these features admirably for small arms ammunition. By looking at the periodic table of elements, the reader will be hard pressed to find another element that is plentiful in nature, but has a higher density than lead. The elements above lead in the periodic table are either rare, volatile, gaseous, radioactive, expensive to extract from the ore or a combination of these properties. For instance, tungsten and uranium are denser than lead, but they are expensive to produce and harder to machine than lead. Hence people use depleted uranium and tungsten only for making special armor-piercing ammunition, but not regular small-arms ammunition. By contrast, lead is very easily available in nature, has high density and is a soft material with a low melting point (which makes it easy to shape). As an extra bonus, it is also a toxic substance.

One of the problems of lead is that it is a soft substance. With firearms before the 1800s or so, this wasn't a problem because the propellants used weren't as powerful and hence the pure lead bullet worked just fine. As propellants got more powerful, the soft lead bullets would get deformed too much before they left the barrel and they would also melt a bit due to the heat. These deformations affected the flight of the bullet. The solution was to encase the lead in a jacket of a harder material such as steel, cupronickel, copper etc.

In the next few posts, we will study the evolution of bullet development.