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.

Wednesday, March 25, 2015

What is Keyholing?

When a person fires a rifled weapon towards a paper target, the usual result expected is that a round hole corresponding to the diameter of the bullet will appear on the target. However, sometimes a larger hole appears, often the hole may appear longer in one direction than the other, such as shown in the image below:

An example of keyholing. Click on the image to enlarge.

These larger holes sometimes resemble a keyhole and therefore, the effect is called keyholing. We will study the causes of keyholing in today's post.

By looking at the shapes of some of the holes in the above target, the reader may notice that some of those holes look distinctly like the shape of a bullet going through the target sideways. In fact, this is exactly what has happened.

Under normal working conditions, the rifling of the barrel imparts a spin on the bullet, which stabilizes it in the air and makes it travel with the nose pointed forward always. However, if the bullet is not stabilized properly when it comes out of the barrel, it will wobble in the air or repeatedly tumble over itself while traveling to the target. Thus, when it strikes the target, it may not strike it with the nose precisely pointed forward and will therefore leave a larger hole.

In the above image, we see three holes. Observe that all three holes are somewhat larger than the diameter of the bullet. The top most hole is shaped like an oblong and was caused by a bullet not flying straight when it impacted the target. The middle hole is more round, but still has a pointed hole on one end showing that the bullet was wobbling in the air when it hit the target. The bottom hole clearly shows that the bullet was toppling end over end and hit the target sideways.

So what causes the bullet instability through the air? There are several causes for this:

  1. Rifling in the barrel could be worn out, therefore it does not impart enough spin to the bullet while it is leaving the barrel. 
  2. The bullet might be undersized and is therefore not engaging the rifling properly.
  3. The rifling twist rate may not be adequate for the weight, shape and profile of the bullet. For example, the M855 cartridge and the L110 cartridge are both designed for the M16A2. The bullet from a M855 (or SS109) cartridge can be adequately.stabilized by a barrel with a 1 in 9 twist rate (i.e.) 1 turn every 9 inches (228.6 mm.) of barrel length. On the other hand, the bullet from the L110 tracer round cartridge does not adequately stabilize at this twist rate and needs a twist rate of at least 1 in 7 (i.e. 1 turn every 7 inches (180 mm.)) for the tracer bullet to stabilize. This is because while the bullet diameters are the same, the weight,  distribution of mass throughout the bullet and the bullet profile shapes are different, which causes the instability. Therefore, M16A2 rifles come with a 1 in 7 twist rate barrel, so that they can be used with both bullet types.
  4. Leading in the barrel could also cause the bullets to not spin as much when they come out of the barrel.
  5. Damage to the barrel near the muzzle may cause the bullets to wobble or tumble as they come out.
  6. The bullet does not always immediately stabilize in the air as it leaves the barrel and needs to travel a little distance in the air before it gains stability. If the target is too close, the bullet may be still wobbling in the air a bit, by the time it hits the target.
  7. The bullet may have hit something on the way to the target, causing it to tumble in the air for the rest of its journey.
An unstable bullet is undesirable because it flies unpredictably in the air and therefore affects the accuracy of the firearm. An unstable bullet also loses velocity faster and it may not transfer as much energy to the target when it strikes it. 

Keyholing is a sign that the bullets are not being stabilized properly. If a gun shoots maybe one keyhole in 500 shots, it may just be due to a bad bullet, but if it regularly shoots keyholes, then that means there is a problem with the barrel or bullets or both, which needs to be fixed.

Sunday, March 22, 2015

Terminology: Flash in the Pan

In English, the expression "flash in the pan" generally means something that starts off very strongly in the beginning, but fails to deliver a result. The origin of this term actually has to do with firearms. You see, back in the early days of muzzle-loading firearms, such as matchlocks, wheel-locks, snaplocks and flintlocks, the main charge of gunpowder was filled in the barrel, but a second smaller charge of finely ground gunpowder (called the "priming powder") was placed in a small pan on the outside of the barrel, called the "priming pan" or the "flash pan". A small hole (called the "touch hole") connected the flash pan to the inside of the barrel.

A flintlock mechanism. Click on the image to enlarge. Public domain image.

 A matchlock mechanism. Click on the image to enlarge. Public domain image.
In the above image, B is the flash pan with the touch hole leading to the inside of the barrel.

To discharge the firearm, the user would typically ignite the priming powder in the pan by applying some method of ignition (whether a lit match, or sparks from a flint striking steel, or whatever). The priming powder lights up in a bright flame and the flame travels though the touch hole and ignites the main charge of gunpowder that is in the barrel, which discharges the firearm and sends the bullet towards the target.

Well, this is how the process is supposed to work in theory, but it didn't always happen this way. Sometimes, the priming powder would ignite with a bright flame, but the gun would fail to fire. This could happen for a few reasons:

  1. The touch hole was blocked by soot and dirt.
  2. The flame from the pan didn't travel through the touch hole to ignite the main charge.
  3. The inside of the barrel was wet and the main charge of powder didn't light.
  4. The user forgot to put the main gunpowder charge in the barrel or didn't load it properly and only loaded the flash pan.
In such situations, the user would see a bright flame and a lot of smoke coming from the flash pan, but after that, nothing would happen.

In the video above, the person deliberately creates a "flash in the pan" effect with his flintlock musket, by only loading the flash pan, but not loading the main charge of gunpowder. As you can see, there is a very bright flame in the beginning, but after that nothing happens.

So there you have it: a flash in the pan is a very flashy start, but with a disappointing result at the end.

Saturday, March 7, 2015

Terminology: Lock and Load

The term "lock and load" is often seen in war movies, especially in scenes with firearms, where a sergeant gives the command to "lock and load" to the troops under him. So what does this phrase mean and what is the origin of it?

The command "lock and load" means to prepare the firearm for firing and put it in condition 1 (i.e.) a loaded magazine is inserted, there is a round in the chamber and the weapon is cocked, but the safety devices are enabled.

So, should the term be "load and lock" or "lock and load" then? Well, it appears that the reason "lock and load" entered into military jargon is because of the M1 Garand rifle.

M1 Garand rifle. Click on the image to enlarge. Public domain image.

In the M1 Garand, to load the weapon, the user first pulls the bolt back and locks it to the rear, and enables the safety in front of the trigger guard. If the bolt is not locked to the rear, it may slam back shut. Once the bolt is safely locked back and the safety is enabled, an en-bloc clip containing 8 cartridges is loaded into the magazine through the top.

Loading a M1 Garand. Public domain image.

When the clip is pushed in, the bolt snaps forward on its own (and if the user is not careful, it may slam into his/her thumb. A common injury among US military personnel was the "M1 thumb"). Once the bolt slams forward, it strips the top cartridge from the clip and the weapon is now loaded. This completes the "lock and load" procedure. The user only needs to disengage the safety and the weapon is ready to fire.

The first time this phrase appeared in a movie was in "Sands of Iwo Jima" starring John Wayne. Since then, the phrase has appeared in many movies (e.g. Saving Private Ryan, Full Metal Jacket etc.) and has become well known in popular culture. It is still used even when the weapon in question is not a M1 Garand. For example, in a M-16, on hearing the command "lock and load", a user pulls back the charging handle and locks the bolt in place, enables the safety, inserts a magazine into the rifle and then pushes the bolt release button to close the bolt.

So why does the procedure enable safeties during the lock phase and before the loading phase. Well, this is because the US military develops its procedures to accommodate all sorts of soldiers, including those who may never have handled a firearm before. As they say, it is better to be safe now than sorry later.

Thursday, March 5, 2015

What is a brass catcher?

Today's post will be on the topic of brass catchers, otherwise called shell catchers. What is a brass catcher and what does it do for the user?

A brass catcher is a device to collect the fired cartridge cases. They come in many shapes and sizes and price ranges. Cheap ones can be found for about $8.50 or so, and expensive ones can cost around $80.00 or so. The images below show some brass catchers:

Click on the images to enlarge. Public domain images.

As you can see by the above images, they come in different shapes and sizes and are made of different materials. The first one is a mesh bag with an attachment that allows it to be hooked to the picatinny rail on top of the AR rifle. The second one is a metallic net shaped into a cylinder, that is attached to the ejection port on the gentleman's rifle. The third and fourth pictures show a plastic one that attaches to a Ruger Mini 14. Some more expensive shell catchers don't need to be attached to a firearm and come with their own frame and stand and can be positioned on the side of the shooter.

When the user pulls the trigger, the firearm shoots a cartridge and then the ejected case comes flying out of the port. If a brass catcher is attached to the ejection port, the cartridge case falls into it and the brass catcher can be detached and emptied later. If the brass catcher is attached properly, it does not interfere with the functioning of the firearm.

So what is the purpose of a brass catcher then? Well, they are pretty handy to have in a shooting range for a number of reasons:

First, while shooting is a lot of fun, a user still has to clean up the ejected cases afterwards. After all, responsible people don't want to damage the environment and leave their trash lying around. If these cases are collected automatically, cleaning up becomes a much quicker job.

Second, some firearms can eject spent cartridge cases quite far away (like 10-15 feet (3-4 meters) or so). If a range has multiple people at the firing line simultaneously and there are no panels in between the shooters, the hot cartridge cases from one user's firearm can end up getting ejected on to the next shooter's face or body parts, thereby disrupting their concentration and creating an unsafe situation. With a shell catcher attached to the firearm, the hot cases will not fly out and hit the next person in line.

Third, if the floor of the firing range is made of a hard substance, such as concrete or rock, then ejected cartridge cases may hit this hard surface and get dented, dinged and otherwise damaged. For people who like to reload ammunition, damaged cartridge cases cannot be re-used. Cases can also roll off somewhere and get lost. With the prices of brass and ammunition being more expensive these days, reloading cartridges is one way for shooters to cut down their costs, especially those who like to shoot large volumes of ammunition. Investing in a cheap shell catcher suddenly becomes worthwhile, as it quickly recoups its cost with the number of cases that it saves.

Of course, there is a caveat to using shell catchers as well. A shell catcher can alter the balance of a weapon somewhat (at least, for those models that attach to firearms), especially as it starts to fill up with empty cartridge cases. For this reason, it is considered good practice to empty the shell catcher periodically after every magazine or two.

Wednesday, March 4, 2015

Firearm Myths - 5 (Fun with Lasers)

We haven't covered any myths for a while, the last article was over 2 years ago. In today's post, we will cover a scene that often shows up in movies and TV. Check out the two screen captures from the popular TV show Sherlock, starring Benedict Cumberbatch as Sherlock Holmes and Martin Freeman as Dr. John Watson.

Click on the images to enlarge.

In the scene, Sherlock Holmes has just arranged a meeting with his arch enemy, Moriarty, and plans to use his pistol on him. Unfortunately for Sherlock Holmes, Moriarty has planned for this and has positioned snipers in the buildings around, and they are pointing their red laser sights at Holmes and Watson.

Now, we look at another scene from a different movie, Captain America: The Winter Soldier.

Scene from Captain America: The Winter Soldier

Here we see that agent Jasper Sitwell is taking a phone call that informs him that he has just been targeted by a sniper and he looks down to see a red dot visible on his tie.

So, do snipers actually use red lasers on their sights? Let's see what the real story is.

First, red lasers are not really very visible in bright daylight, a fact we covered a while ago. Green lasers are a bit more visible, but use up a lot more battery power. So, the scene from Captain America, where a bright red laser dot shows clearly in broad daylight, is a bit of Hollywood movie magic and is not possible in real life.

Now let's look at another thing about laser sights. They are useful to acquire targets quickly at short range, because the user can see exactly where the weapon is pointing at, without peering through the weapon's other sights, especially in low light conditions.

However, laser sights are not useful for long range snipers, due to a few reasons:

  1. The primary goal of a sniper is to stay hidden. If a real sniper used a laser like the types shown in the images above, everyone would know where the sniper is, because they can just follow the laser beam back to the source.
  2. The target will also know that he or she is being targeted and can possibly attempt to take evasive action.
  3. Laser light travels in a straight line, but bullets don't. A laser sight completely ignores the effects of gravity, wind, air density etc. This is why rifle sights have adjustments for elevation and windage
For these reasons, the scenes with the snipers are highly questionable. They look pretty good on TV though.

Sunday, March 1, 2015

All About Scopes - IX

In our last few posts, we looked at scopes, both from the inside and the outside. But how does the scope get attached to a rifle. We will study how scopes are mounted in today's post.

Some rifles, such as the Steyr AUG, are already manufactured with built-in scopes,
Steyr AUG Assault rifle. Click on image to enlarge.
Image licensed from Steyr Mannlicher GmbH & Co. under the Creative Commons Attribution 2.0 License.

In many other rifles, they already come with some sort of mounting system built in (e.g. Weaver rail, Picatinny rail etc.). Examples of this would be the M4, H&K 416 etc. Even if there is no rail system built in, many modern rifle manufacturers usually have a couple of holes drilled into the receiver, so that the user can attach a scope mount base later. As for rifles that were built before scopes became popular (e.g. the Mosin Nagant rifle), a scope can still be attached to these, either by replacing the standard rear sight with a sight that allows a scope to be mounted, or by drilling the appropriate holes into the receiver and/or stock and attaching a scope base. Of course, the last couple of procedures are probably best done by a qualified gunsmith.

Assuming this is a relatively modern rifle, the receiver should already be pre-drilled or grooved to attach a scope base. The first step is to remove any filler screws and degrease the screw holes, then mount the scope base on to the rifle, applying a little bit of loctite or oil to the screws before screwing them in. '

The next step is to attach the scope rings to the base. These come in two halves, which can be separated.

Scope rings

The bottom of the scope rings are shaped with dovetails to attach to the scope base securely. The next step is to ensure that the scope rings are aligned correctly. To do this, the user uses a scope ring alignment tool. This consists of two precisely machined rods with pointed conical tips. The user slides one rod into each ring and tries to adjusts the alignment of the two scope rings until the two pointed ends of the two rods are almost touching.

Scope Ring Alignment Tool by Wheeler

Once the two scope rings are aligned properly, the user unscrews the top halves of the two scope rings, drops the scope in to the lower halves and then screws the top halves back on. Care is taken to mount the scope a little forward (i.e. give it eye relief), so that there is enough gap between the scope and the user's face to account for any recoil after the rifle is fired.

Once the scope is attached, the next step is to align the sights properly. One cheap way to do this is to remove the bolt from the rifle, then aim it at a target by looking through the barrel from the back, then ensure that the scope crosshairs are also pointing to the same point on the target. Of course, this only works for bolt-action rifles and doesn't work with lever action or semi-auto rifles. For these rifles, a laser bore sighting tool is used instead. These usually slide into the muzzle, or can be placed in the chamber. Either way, they project a laser beam, which can be pointed to a target and then the user can check if the scope crosshairs are also aligned to the same point or not.

In chamber bore sighting tool.

Bore sighting tool.

After this, the user needs to still take the rifle out to the range and align the sights properly by firing test-groups at a target.

The next two videos by Midway USA show how this process is done in detail:

Happy viewing!