Saturday, April 25, 2015

Rocket Balls and the Volition Repeating Rifle

We have looked into several developments for metallic cartridges in the last few posts. In today's post, we will look at a very early development in metallic cartridge history. The cartridge we will study today is Walter Hunt's Rocket Ball cartridge and the rifle that was built to fire it, the Volition Repeating Rifle.

A long time ago, we had studied about expanding bullets and the Minie ball. These were bullets produced with a hollow conical cup fitted at the base of each bullet. When the rifle was fired, the cup would move up and expand the base of the bullet, so that it would engage the rifling grooves and also make a tighter gas seal, so that the gases would mostly use their energy to push the bullet out of the barrel, instead of escaping out around the sides of the bullet. However, expanding bullets like the Minie ball were used with muzzle loading rifles. This meant that a user would pour in gunpowder first, then drop in the bullet, then ram everything down the barrel, then cock the weapon and add a percussion cap, all this before the user could pull the trigger. This meant loading took a while.

In 1848, a gentleman named Walter Hunt from New York, invented a new type of metallic cartridge that he called the Rocket Ball. A copy of his patent claim (US 5701) is available online,

Patent for the Rocket Ball Cartridge
Click on the image to enlarge. Public domain image.

Like the Minie ball, this bullet also has a deep hollow in the base. This hollow serves the same purpose as the Minie ball, (i.e.) it serves to expand the base of the bullet when it is fired and makes a tighter gas seal. However, the design also has a second use for that hollow space -- Walter Hunt also filled the hollow with gunpowder and sealed the base with a cap with a small round hole in its base for ignition. In the above diagram, A is the cap in figure 1, shown attached to the bullet. In figure 3, the cap A is shown disassembled from the bullet. In figures 3 and 4, you can also see the small hole in the middle of the cap, represented by F. The gunpowder was packed into the cavity D. The line GG represents a thin waterproof seal, through which the priming flame could penetrate to ignite the gunpowder in D. The seal prevented the powder from getting spoiled by moisture, or falling out from the back of the cartridge.

Upon firing the gunpowder, the base of the bullet would expand and separate from the cap, which would also expand and seal the breech from the back. The bullet would be pushed out of the barrel, leaving the cap behind resting on the breech plug. Upon loading the next cartridge from the breech, the cap would be pushed forward and end up in front of the next bullet. Upon firing the next cartridge, the old cap would leave the barrel ahead of the next bullet fired, thereby wiping the barrel on the way out and cleaning some of the powder fouling.

Therefore, this was not only one of the early metallic cartridges invented, it was also an early type of caseless ammunition! Unlike the Minie ball, loading this new ammunition was much faster because bullet and gunpowder were all contained in a single package and the user only needed to add the percussion cap.

To fire this new type of ammunition, Walter Hunt also developed a firearm called the Volition Rifle. It was one of the first lever action weapons invented. The rifle was somewhat complicated to build and contained a number of small delicate parts. Therefore, it was not a commercial success and only a few examples were built.

However, the idea of a lever action repeating rifle firing a self-contained cartridge was picked up by other people, notably a gentleman named Mr. Lewis Jennings, who invented a better lever action rifle called the Jennings rifle, which was manufactured between 1849 and 1852, Like the Volition rifle, this was also fired by an external percussion cap. While Lewis Jennings took care of marketing the rifle, the manufacturing was subcontracted to a company called Robins & Lawrence Arms Company in Vermont.

A Jennings Rifle. Click on the image to enlarge.

It is interesting to note that the foreman of the Robins & Lawrence Company factory during this time, was a gentleman named Benjamin Tyler Henry. He worked with two other employees of the factory, Horace Smith and Daniel Wesson, to improve the rifle design. We will read more about these three employees and their further inventions in the next article.

The Jennings rifle was only manufactured for three years before production stopped in 1852, resulting in heavy losses for the company's investors. However, the Volition and the Jennings rifles showed the concept of a rapid-firing repeating rifle was possible. We will study further developments in the next article.

Monday, April 20, 2015

What is Season Cracking?

In our last few posts, we studied the process of manufacturing brass cartridges, as it was done in the 19th century and in modern times. In today's post, we will study a topic related to brass cartridges, a phenomenon called Season Cracking.

Quite often, older brass cartridges may be seen to develop cracks in the case, such as the examples shown below:

.35 Remington cartridge case split by "season cracking". 
Image licensed under Creative Commons Attribution 3.0 Unported license by DrHenley at wikipedia.

Click on the image to enlarge. Public domain image.

The presence of a crack like this means that the cartridge case is unsafe to use. The first reports of this phenomenon came from British forces stationed in India in the 1800s. They noticed that brass cartridges tended to crack after the end of the monsoon season. At that time, they were not sure why this was happening, only that it seemed to happen a lot after the monsoon season ended and dry weather returned. Therefore, they attributed this problem to the change of seasons and called it "season cracking".

It was not until 1921 that the real reason for the cracked cases was explained. As it happened, monsoons in India were the worst time of year for military operations to be conducted, as the rain storms were often very strong and the ground would get very muddy and unsuitable for travel and transport. Therefore, armies would stay in their barracks and try to keep their ammunition supplies dry during the monsoon season. British forces would often store their ammunition in horse stables during this time and this was where the problem started.

You see, urine contains ammonia and when horses were kept inside the stables for a long time, they had a lot of horse urine to go around. The ammonia reacts with the copper in the brass, to form a cuprammonium ion, which happens to be soluble in water. The high humidity in the air causes the cuprammonium ions to dissolve and wash away, which causes cracks to form.

Examples of brass cracking due to ammonia reacting with the copper in the brass.
Click on the image to enlarge. Public domain image.

Once the cracks start to form, the residual stresses from drawing the cartridge cases during manufacture cause the cracks to widen. Once the cracks reach a certain size, the case can suddenly fracture. One way to reduce this problem is to remove the residual stresses from the cartridge cases by annealing them after the drawing process, which we studied earlier.

The correct explanation for this problem was first given by H. Moore, S. Beckinsale and C.E. Mallinson in 1921.

As it happens, this problem was first found with brass cartridge cases, but it can happen to any alloy that contains a good amount of copper (e.g. bronze, copper etc.). Therefore, it could happen to copper jacketed bullets or bronze parts etc.

Also, it doesn't happen only because of horse urine, but can happen anywhere that ammonia is present. This means it can happen with cat urine, dog urine etc., as well as common household cleaning chemicals that contain ammonia, such as Windex glass cleanerBrasso polish etc. So, if the ammunition is stored next to a cat litter-box, or near cleaning fluids that contain ammonia, this could cause the cases to form cracks. The first image in this post shows a cracked .35 Remington cartridge and the photographer states that he had cleaned the cartridges with Brasso and then stored them in a place with high humidity for some years.

Sunday, April 12, 2015

Manufacturing Cartridges: More Modern Methods

In our last four posts, we looked at how cartridges were made in the Kynoch factory in the 19th century. We will briefly look at how cartridges are made now. It is interesting to note that while technologies have improved to where machines can do the work previously done by humans, many of the principles still remain the same.

First, we look at the process of cartridge case forming, as it is done in a factory today:

Click on the image to enlarge.

The image above shows the process of drawing the brass case gradually and annealing it at multiple stages, until it reaches the required length (steps 1 - 5). Then it is trimmed to size in step 6 and the case head (the base) is shaped (step 7) and then the neck is formed (step 8). Finally the rim and mouth are machined to the final cartridge specification.

During the process of shaping the case head, a tool called a headstamp bunter punch is used to shape the base and form the primer pocket, as well as add manufacturer information to it.

Base of a 8x68 mm. rifle cartridge made by RWS. Click on the image to enlarge.
Image licensed under Creative Commons Attribution-Share Alike 3.0 Unported License by BreTho at wikipedia.

Headstamp bunter punches. 

A headstamp bunter punch has a cylindrical protrusion to make the primer pocket and has raised lettering on its face to stamp the manufacturer information onto the base of the cartridge. Typically, the information lists the manufacturer and the caliber of the cartridge. Some cases, especially those used by military forces, also have the year of manufacture stamped as well. Some military cartridges may even have a code indicating the location of the factory, as well as the month that the cartridge was made. In the above image, we see that the cartridge is made by RWS (a German manufacturer) and it is a 8x68 mm. S cartridge.

Now, let us look at some videos of manufacturing processes at various factories around the world. The first video was produced in the 1940s by British Pathe and shows a factory in South Africa:

In this particular factory, they cast their own brass billets from scratch. Note that some of the processes used in this factory were still manual and done by humans. However, the really dangerous processes of loading the primers and the propellants have been automated by this time.

The next video is from Silver State Armory and is a slideshow of their manufacturing process. Note that the process is pretty similar to what was described in the previous posts.

This video is more of a slide show and describes the various stages of manufacture, but does not show the actual machines involved.

The next video is produced by the NRA and shows ammunition being made by Hornady (for non-US readers, Hornady is a well-known manufacturer of ammunition in the US):

This video shows more of the manufacturing process, as well as some of the machinery used. Hornady uses mechanical force to form bullet jackets, rather than heating and molding them. The video shows the complete process, including testing, quality control and packaging the cartridges.

The next video shows ammunition being manufactured at Winchester:

The video shows the process starting from melting the raw materials to make brass and explains the process, along with showing some of the machinery used to manufacture cartridges. The video also shows the manufacture of shotgun shells as well.

Finally, here's a long video from Field Sports (a British channel), showing the process of cartridge manufacture at RWS (a large manufacturer from southern Germany):

At 22 minutes long, this is a bit longer than the other videos, but it also covers the manufacturing process in pretty good detail.

Happy viewing!

Wednesday, April 8, 2015

Manufacturing Cartridges in the 19th Century - Part IV

In our last few posts, we saw how they manufactured cartridge cases, primer caps and bullets in the 19th century. In today's post, we will see how these components were combined together to form the finished cartridges. As before, this is the process that was followed at Kynoch, a large British manufacturer of ammunition and the equipment they used was the latest available for that era.

Since Kynoch manufactured large quantities of cartridges daily, they used machinery to help load the cartridges. The process started by placing a bunch of cartridge cases in frames of up to 100 cartridge cases per frame. Each frame was then taken to a loading room to be filled with gunpowder.

For safety reasons, only minimal personnel were allowed into each loading room. The gunpowder was placed in a container  that was attached to the wall outside of the loading room. The container had a rubber pipe attached to the bottom of it, and the other end of the pipe ran into the loading room. The other end of the pipe also had an accurate measuring device attached to its end that allowed it to dispense a precise amount of powder each time. A worker would use one hand to move the pipe from case to case and the other hand to work the measuring device and dispense a measured quantity of powder in each case. Each worker could easily fill around 30,000 cartridge cases per shift.

After the cases were filled, the frames were then taken to another room, where wads were added to the cartridges. The purpose of a wad is to reduce the air pocket between the bullet and the gunpowder in a cartridge case. Each wad was placed on top of the cartridge case and then pushed into the case using a hand rammer tool.

After adding with wads, each cartridge case had a bullet placed in the mouth and then, each bullet was pushed in. After that, the whole cartridge was inserted into a swedge, which would close the lip of the case and crimp it. This was done to make the case fit the bullet and prevent it from slipping out from the cartridge case. The finished cartridges were then packed in boxes and shipped out from the factory.

Cartridges made with this process could be placed under water for a fortnight and still work fine. Leading manufacturers like Kynoch could manufacture ammunition that was far superior to cartridges produced by hand by amateurs and low-end gunsmiths, and at a much faster rate as well.

While this process involves some human labor, Kynoch was working on making machinery to fully automate the loading process.

For loading .303 ammunition, Kynoch also made machinery for weighing, cutting and loading the strings of cordite.

In the next post, we will look at some modern methods of manufacturing cartridges.

Sunday, April 5, 2015

Manufacturing Cartridges in the 19th Century - Part III

In our last couple of posts, we studied how the cartridge cases and primers were manufactured during the middle of the 19th century. In today's post, we will study how the bullets for the cartridges were made. As before, we will study how the process was done at Kynoch, a large British manufacturer of ammunition, which was using the latest technologies and machinery available during that era.

While we have studied cast lead bullets in the past, by the 19th century, the casting method was considered too slow for mass production. Therefore, bullets were made in quantity using machinery. We will see how this was done in that era.

The first order of business was to prepare the lead for bullet making. Pure lead was not used for bullet manufacture as it is too soft. Instead, lead was melted and then, zinc or tin were mixed with the lead to harden it. This lead alloy was then forced out into long round ropes of metal, which were then coiled and loaded onto bullet-making machines.

The bullet-making machines at Kynoch were marvels of mechanical technology at that time. The best machines were capable of measuring out a length of metal, cutting it from the rope, feeding the cut piece into a die shaped like a conical bullet, forcing it in with a conoidal punch and then ejecting the finished bullet into a box. The bullets were then regulated in a press, to ensure that they were as cylindrical as possible. Each bullet was then placed in a lathe and wrapped with a paper patch, which was cut off and twisted while the bullet was revolving in the lathe. The paper patches were then waxed on to the bullet and the bullets were now ready to be loaded.

There were a few advantages of making bullets this way, versus the old casting process. For one, it was faster to manufacture bullets using this method. The bullets were also much more uniform in size, shape and weight than cast bullets. In addition to this, the possibility of casting defects, such as air pockets and hairline cracks, did not occur on these machine-made bullets.

The factory at Kynoch not only made lead bullets, but also made composite bullets (e.g.) jacketed bullets. To make these, the outer jacket was made of a copper alloy. The Kynoch factory used an alloy of 80% copper, 20% nickel, with small quantities of manganese, iron and silicon. This alloy was chosen because it is tough and hard and produces a shiny surface that doesn't tarnish easily. The alloy has a tensile strength of 27 tons per square inch. The alloy was rolled into sheets of 0.04 inches thickness. These sheets were then made into jackets using a process similar to how cartridge cases were made, which we studied earlier (i.e.) the round blanks are punched out from the sheet, then each blank is cut out and made into a cup and then passed to a drawing machine, where the jacket is drawn out gradually to the required length by multiple drawing operations. Unlike making the cartridge cases, annealing and pickling in acid were not necessary between each drawing stage and seven drawing operations were sufficient to elongate the blank into a outer jacket for a .303 bullet. The inner part of the bullets (the cores) were made of a lead alloy. Lead was mixed with 2% antimony and squirted into rods of the required diameter. These rods were cut into pieces of the length desired and each piece was placed into a jacket by hand. The composite bullet was then forced into a die, so that the edge of the jacket was turned down over the base. The final finishing processes consisted of adjusting the diameters of the bullet, trimming and adding the rings at the base.

It may interest the reader to know that some jacketed bullets are still made today, using a similar process. Here's a video showing how Hornady makes jacketed bullets today:

In the next post, we will study how the cases, primers and bullets were brought together to load a complete cartridge. Until then, happy viewing!

Tuesday, March 31, 2015

Manufacturing Cartridges in the 19th Century - Part II

In our last post, we studied how metallic centerfire cartridge cases were manufactured in large factories in the 19th century. We will continue our study of the manufacturing process in today's post.

Where we last left off, we'd just studied how the brass cases were shaped. The next step is to attach primers to the cases. In the 19th century, primers were made of copper caps. The process worked as follows:

The copper caps are made by punching blanks from copper sheets and then formed into small cups (similar to the cartridge cases in the previous post). A bunch of these caps are placed onto a plate with indentations in it to hold the caps in place. Then, this plate is covered by two other plates, which have holes drilled into them, corresponding to the positions of the caps, when all three plates are placed on the loading frame. The top plate can move horizontally for a short distance and when it is moved, the holes on this plate move clear of the holes in the middle plate, and thus it forms a bottom to the holes of the top plate. The shock-sensitive priming material is made damp with water and carefully spread over the top plate, so that it fills all the holes drilled into it. The surplus priming powder is brushed off. Then the top plate is moved back into position, where its holes correspond to the holes in the middle plate and the caps in the bottom plate. The priming material thus falls through the holes into the priming caps. The caps are then moved to a press and a tinfoil disk is pressed on to the priming powder and then varnished over with spirit varnish, to make the caps waterproof.

Manufacturing the priming powder and filling the caps were both considered as dangerous operations in the 19th century. Therefore, the British parliament passed a law that specified that only one person was allowed into the room where the priming powder was made and the room where the caps were filled. This law was to ensure that if there was an accident, there would be minimum casualties.

The caps are placed on the bases of the cartridge cases prepared in the previous post and then they are pushed into place by a descending rammer and are now ready to receive the propellant powder and the bullets.

In our next post, we will study how the bullets were made and the propellants loaded in the 19th century manufacturing process.

Sunday, March 29, 2015

Manufacturing Cartridges in the 19th Century

In today's post, we will look at how brass centerfire cartridges were manufactured in the 19th and early 20th centuries. The process we will look at was what was used at Kynoch, a large British manufacturer of ammunition. The brand name "Kynoch" is still used today to sell cartridges, even though they have been merged into a larger company.

The Kynoch factory during this time period, was located in Witton, an inner city area of Birmingham, England.  The factory had several hundreds of machines in a single building, turning out cartridges of many shapes and sizes. The machinery used there can be considered as the latest technology for that era.

The process we will study today is what was used to manufacture solid-drawn brass cartridge cases. The first step in the process is to make flat sheets of a type of brass called "cartridge brass". The brass sheet metal is then taken to a machine that punches out circular blanks from the sheet.

Public domain image.

The image above shows a blank to be used to manufacture cartridges for a Mauser rifle. The next step is to put the blank through a drawing machine, where it is forced through a die with a tapering aperture by a ram under high pressure. This produces an object that is shaped somewhat like a cup or a thimble, as shown below:

Public domain image.

Naturally, the pressure applied when shaping the cups puts stress on the metal. Therefore, the cups are then annealed. Annealing is a process of heating the object until it is glowing hot and maintaining the temperature for a while and then rapidly cooling it by quenching in water (a previous version of this post incorrectly mentioned "letting it cool back slowly to room temperature in a room with no breeze blowing". Brass can be annealed by cooling rapidly with no ill effects. Steel, on the other hand, has to be annealed by letting it cool slowly. Cooling steel rapidly hardens it instead of softening it, whereas brass can be cooled rapidly.) The process of annealing softens the metal and removes the internal stresses caused by the shaping process. After annealing, the cups are then pickled in sulfuric acid to clean them. They are then forced through the drawing machine again to increase the length of the cartridge case (as shown in step 3 in the image below). The process of annealing, cleaning in acid and then forcing through the drawing machine is repeated multiple times, depending on the type of cartridge case, and the cartridge case is elongated each time until it reaches the size as shown in step 4 of the image below.

Public domain image.

Then the neck is formed by pushing the cartridge case through a press to give it the bottle-necked shape, as shown in step 5 in the image above. The base of the cartridge and the rim are formed by a powerful horizontal punching machine, which forces the empty case into a die to form the base and the cap chamber, as shown in step 5 and 6 in the image above. Finally, two tiny holes ("flash holes") are pierced through the cap chamber, as shown in step 6.

The cartridge cases are then trimmed to the required length and the rims are machined to remove sharp edges  and then, a primer cap is applied to the base of each case by a descending rammer and they are ready for loading. We will study exactly how this was done in the next post.

These days, many cartridge manufacturers use an extrusion process to form the cartridge cases, as it is faster and  more economical (we will study that shortly). However, there are a few manufacturers around, such as Norma, Lapua and RWS, that still use the traditional process to make premium quality brass cases.