Thursday, September 27, 2012

Firearm Malfunctions: Squib Loads

In our last post, we looked at hang fires and dud cartridges. In this post, we will look at another firearm malfunction usually caused by bad ammunition: squib loads.

So what is a squib load exactly? A squib load is where a cartridge is too weak to push the bullet out of the barrel of the gun, so the bullet gets stuck inside the barrel.

Here's what happens when a user encounters a squib load: The user pulls the trigger of the firearm, the hammer strikes the cartridge properly, but instead of a loud bang with the usual recoil, the firearm makes a softer "poof" sound and the recoil felt is much less. Instead of smoke coming out of the end of the barrel, it comes out of the ejection port.

So what causes squibs to happen? Often, this is because of poor quality control during cartridge loading. The person may not add enough propellant into the cartridge, or even forget to put any propellant into the cartridge. Sometimes the primer may explode without igniting the propellant. Also, the ammunition may not have been stored properly and the propellant inside could have degraded. These are problems usually seen with cartridges that are reloaded by inexperienced people, but they may also happen with factory loaded ammunition (especially if the manufacturer has a poor reputation for quality control). It may also happen that the bullet is misshapen or a bit too large for the barrel, which could also cause it to get stuck inside.

When this happens, it could lead to a very dangerous situation. If the user doesn't notice the squib cartridge and fires another cartridge with the barrel blocked, then there is a very good chance that the barrel could become bulged and the firearm ruined. There is also the possibility that the barrel could explode and lead to possible injury or death to the user and bystanders.

Therefore the user should pay careful attention to his firearm when shooting. If the firearm emits a quiet "pop" sound instead of a loud noise and if there's a lot less recoil felt, then a squib load should be assumed. The user should wait for a little while to make sure this isn't a case of hang fire and then unload and disassemble the firearm and remove the bullet stuck inside.

With all that said, here's what a squib load sounds like:

As you can see, the user encounters a squib at around 1:40 in the video. He wasn't paying much attention and thought it was just a misfire and was at the point of clearing his pistol to shoot another cartridge when the range safety officer yelled "stop" at him and pointed out that the previous cartridge was a squib load. You can hear the difference in sound when the squib fires.The user notes in his video that the cartridges were personally loaded by him and that he hadn't paid as much attention when reloading them and it is a very good thing that the range safety officer noticed what had happened and stopped him from shooting any more.

Monday, September 24, 2012

Firearm Malfunctions: Hang Fires and Dud Cartridges

In our last post, we looked at some reasons for firearm malfunctions. In the next few posts, we will discuss these reasons in more detail. In this post, we will look into the topic of hang fires and dud cartridges.

So you've just aimed at the target and pulled the trigger of your firearm and the hammer falls on the cartridge and then, nothing happens. You may have just experienced either a hang fire, or a dud cartridge. What is going on here?

First, let us examine the phenomenon known as "hang fire" (also known as "delayed discharge"). This is when the trigger is pulled and the hammer releases properly, but there is a perceptible delay between when the hammer is released and when the firearm shoots. The delay time can vary: it can be only a fraction of a second to many seconds later. This may have the effect of throwing off the shooter's sense of timing and cause him/her to miss the target. In the case of propeller driven aircraft from World War I and World War II, the result was sometimes more catastrophic. You see, in those days, fighter aircraft used to have an interrupter gear (a mechanism invented by a Dutch man, Antoine Fokker during World War I) that allowed the aircraft to shoot its guns through a rotating propeller. The mechanism ensured that the aircraft's guns would only fire when the propeller blade was not in front of them. However, with hang fire happening, this could cause the bullets to come out a fraction of a second too late and strike the rotating propeller blade.

In the early days of firearms such as matchlocks and flintlocks, this is how all firearms worked -- there was always a delay from pulling the trigger to when the firearm discharged. In fact, the inventor of the percussion lock specifically designed his firearm to solve this delay issue. However, the issue was not completely solved and still happened because the quality of the powder wasn't always good quality in those days. It is still a problem in modern times too, because even if the production methods and quality of powder have improved, it may still happen if someone stores the ammunition improperly, or if the ammunition is too old. Ammunition which has been stored in damp conditions or exposed to penetrating cleaning solvents such as WD-40 may experience hang fires or become dud cartridges. Reloaded cartridges may also experience this issue if they haven't been cleaned properly prior to reloading (for example, the primer pocket in the cartridge may be partially blocked with residue). Finally, factory manufactured cartridges may also have this issue if they are very old or if they have been manufactured using improper methods and bad quality control.

When a hang fire occurs, the primer goes off, but the main propellant in the cartridge doesn't burn right away and it burns slowly until it builds up enough pressure to push the bullet out of the crimp of the cartridge and out of the barrel. This may take a few seconds to accomplish.

A dud cartridge will not fire at all. The reasons for this happening are similar to that for hang fire (i.e.) bad ammunition or incorrect storage of the ammunition. Other reasons that could cause dud cartridges include putting in a bad primer cap or forgetting to load propellant in the cartridge.

So what should a user do after they have pulled the trigger and nothing happens? Is this because of a dud cartridge or is it hang fire and how can the user tell the difference?

The user should continue to point the firearm in a safe direction for about 30 seconds, just in case it is a hang fire. If the firearm doesn't shoot after 30 seconds, the user may then conclude that the cartridge is a dud and remove it from the firearm. It is not a good idea to start examining the firearm right after it fails to fire because  it may just be delayed due to hang fire.

The video below is an example of what NOT to do:

The user is the above video is very lucky to be alive. After his gun failed to fire, he immediately decided to look down the barrel to see what was wrong, instead of waiting for 30 seconds in case it was a hang fire. He was very lucky that the bullet didn't hit him when the gun finally fired.

If the firearm hasn't fired after 30 seconds, then it may be concluded that this is not a hang fire and that the cartridge is a dud. The cartridge may then be removed, but it should be disposed off safely. Why? Because there is a dangerous possibility that the cartridge can fire later on (for example, it may not have fired because the primer cap was bad, but the propellant inside the cartridge is still good and can go off if exposed to flame or heat).

Some ammunition factories have very poor quality control and manufacturing methods, and their ammunition is sold especially cheap. For example, .303 cartridges manufactured by POF (Pakistan Ordinance Factory) have a reputation for being of very poor quality and experiencing several hang fires and dud cartridges in every box of ammunition and several Enfield users recommend not buying them from this manufacturer at all. The video below shows one user's experience with 20 cartridges made by POF:

As you can see from the video, of the 20 cartridges fired, 8 were duds and didn't shoot at all and many of the remaining experienced hang fire, which can clearly be seen in the video when the user shoots. The user does not save any money by purchasing such cheap low quality ammunition, as it is unreliable and quite dangerous to shoot with.

Wednesday, September 19, 2012

Firearm Malfunctions: Types of Malfunction

In our previous post, we studied about the stovepipe jam. But we got a little ahead of ourselves there. What we should have studied first is a general overview of different types of firearm malfunctions, before going into specific details. We will do that in this post.

Before we start, it should be noted that not all firearm malfunctions are equal. Some of the malfunctions are relatively minor and can be easily fixed, whereas other malfunctions are much more serious and can damage the firearm or be dangerous to people nearby. Proper cleaning and maintenance procedures can go a long way in preventing malfunctions.

There are two main categories of firearm malfunction causes, with numerous subcategories within each. The two main categories of malfunctions are:
  1. Ammunition malfunction: The ammunition doesn't work as expected. This is also called a "misfire"
  2. Mechanical malfunction: There is some problem with the firearm's mechanism, which causes it not to work properly.

Ammunition Malfunction

Within this category, we have some subcategories:
  1. Hang fire: This is also called "delayed discharge". The trigger is pulled, but there is a delay from when the trigger is pulled to when the firearm shoots. This was common with old-style firearms such as matchlocks and flintlocks because of poor quality of black powder. It also sometimes happens with modern ammunition though, especially if the ammunition has been stored improperly for a while. 
  2. Dud cartridge: The trigger is pulled and the hammer strikes the cartridge firmly, but the primer cap or propellant of the cartridge doesn't ignite and so nothing happens. If a dud round is encountered, the standard procedure is to keep the firearm pointed  at a safe target and wait for 30-60 seconds, to ensure that this is not a case of "hang fire" that we just studied in the previous paragraph. If it doesn't fire after this time, then it might be because of a dud cartridge. In this case, the procedure is to eject the round and dispose of it properly, as it may still be dangerous.
  3. Squib load: This is often caused due to insufficient quantity propellant in the cartridge case or because the ammunition quality was very poor. When this happens, the ammunition does not have enough force to push the bullet out of the barrel and the bullet stays stuck inside it. This causes an extremely dangerous situation if the stuck bullet is not removed, as the next cartridge fired will cause another bullet to impact the stuck one and may cause the weapon to explode.

Mechanical Malfunction

Within this category, we have some subcategories as well. Mechanical malfunctions are usually caused by dirt and rust, damage to parts, poor maintenance procedures, bad design etc. Some of its subcategories are:
  1. Failure to feed: Due to some mechanical problem, a cartridge could not be properly loaded into the firing chamber. Some of the reasons this happens is if the magazine isn't properly inserted into the firearm, or if the user forgot to manipulate the slide after the magazine is inserted, or there may be some damaged parts (dents or bulges) in the firearm, or there may be some dirt that causes it not to feed the cartridges properly etc.
  2. Failure to eject: The cartridge was fired, but due to some mechanical problem, it could not be ejected out of the weapon properly. The stovepipe jam that we studied in the previous post is a case of failure to eject.
  3. Failure to extract: The fired cartridge case could not be extracted properly and as a result, a second cartridge is loaded into the chamber without the first one being removed from it.
  4. Slamfire: This sometimes happens when a cartridge is ejected and a new one is moved into the chamber. The force of chambering the new cartridge sometimes causes it to fire, without the user intending it to do so. This is extremely dangerous, especially if a semi-automatic weapon unexpectedly goes full-auto when the shooter is not expecting it.
  5. Failure of safety devices: This may happen to a poorly maintained firearm, where the safety devices do not work and the firearm goes off accidentally without the user expecting it.
We will study all these malfunctions in detail in the following posts.

Monday, September 17, 2012

Firearm Malfunctions: Stovepipe Jam

In the next few posts, we will study some cases of malfunctions in firearms. The first one we will study is the stovepipe jam.

A typical stovepipe jam. Click on image to enlarge.

Note that in the above image, an empty cartridge case is stuck in the ejection port at the top of the pistol.  This is an example of a stovepipe jam. The reason that this is called a stovepipe jam is because the empty cartridge case resembles the chimney pipe of an old fashioned cooking stove.

A stovepipe jam usually occurs in semi-automatic or fully-automatic firearms and is a failure-to-eject malfunction (i.e.) the cartridge that was just fired did not get ejected from the firearm properly and the cartridge case is partially stuck in the ejection port. This means the weapon cannot load the next cartridge into the chamber properly and will not fire.

There are four major causes of stovepipe jams:
  1. Limp wristing the weapon: We already studied the subject of limp wristing a month ago. By not holding the firearm strongly enough and not offering enough resistance and rigidity to the recoil forces of the firearm, the firing action may not complete its cycle properly and hence a jam occurs. This is more commonly seen when using pistols.
  2. Old or bad ammunition: The propellant in the cartridge case may have degraded sufficiently due to age, or the case may not have been filled with enough propellant. Either way, the burning propellant doesn't generate enough power to cycle the action properly and so the cartridge doesn't get fully ejected by the time the slide returns back.
  3. Bad ejection mechanism: Either the return spring of the slide may be too strong or the ejector spring that ejects the old cartridge is too weak. In either case, the slide moves back and then gets pushed forward and starts to close before the old case is ejected. Therefore, the old case gets caught before it has a chance to fully leave the firearm.
  4. Spin back: The old cartridge case does get ejected, but it hits something on the way out (e.g. the ammunition belt, or the drum, or the side of the ejection port) that causes it to spin back into the ejection port instead of going out of the weapon. Some rifles are more susceptible to this than others: e.g. the Stoner 63A, which was used by SEALs in Vietnam, occasionally suffered this when configured with a snail-drum magazine which fed from the left hand side. It did not exhibit this issue when configured with a box magazine fed from the right hand side.
Stovepipe jams are relatively easy to clear. We will study how to clear firearms at the end of this series. For now, we will continue studying other types of malfunctions in the following posts.

Thursday, September 13, 2012

Picatinny Rails

When it comes to mounting accessories on to small arms, a picatinny rail is usually what is used to attach an accessory to the firearm in question. We will study this piece of technology in this post.

For many centuries, people developed many different accessories that could be attached to firearms, such as bayonets, telescopic sights, tactical lights etc. What was missing though was a standardized way to attach such accessories to a firearm. The US military decided to change all that and commissioned the Picatinny Arsenal in New Jersey to develop a standard for a mounting bracket that could be used to attach various devices. The Picatinny Arsenal developed a specification for a mounting rail called the MIL-STD-1913 rail, based on some work done by the A.R.M.S company back in the early 1980s. The specification was officially accepted by the US military on February 3rd 1995. This specification was also later adopted by NATO forces as the STANAG 2324 standard. Since the rail specification was developed by the Picatinny Arsenal, people often refer to the it as the "Picatinny rail".

Cross-sectional and side views of a picatinny rail. Click on images to enlarge. Images are in the public domain.

It consists of a rail with a number of raised ridges separated by spacing slots. The raised ridges are shaped like the letter 'T' in cross-section. Devices may be attached by sliding them on to the rail and then clamping them if needed with thumbscrews, bolts, levers etc.

Different models of picatinny rails made by various manufacturers. Click on images to enlarge 

Originally, the picatinny rail was meant to be used for mounting telescopic sights and was placed on the rifle's receiver, roughly where the rear sight should be. Nowadays, manufacturers place multiple rails on the firearm, so that many accessories may be attached simultaneously. Incidentally, these rails do not need to be attached to a rifle, many pistols can be fitted with them too.

HK-416 with multiple picatinny rails. Click on image to enlarge.
Image is licensed under the Creative Commons Attribution-Share Alike 2.0 Generic license by user Dybdal at Wikipedia 

In the above image, we see a Heckler and Koch HK416N assault rifle used by the Norwegian army. This firearm has multiple picatinny rails on it, as can be seen in the image above. The user has attached a telescopic sight as well as a vertical foregrip accessory to the firearm and there's room to attach other accessories as well, such as a tactical light, laser aiming module etc.

Many rifles and handguns now come with picatinny rails on them. While the original purpose was to use it to mount telescopic sights, there are now manufacturers of other accessories, such as carrying handles, tactical lights, bayonets, bipods, laser lights etc., who make their accessories compatible with picatinny rails. Therefore, the same accessory can be easily mounted on to multiple firearms.

Thursday, September 6, 2012

What is the difference between 5.56mm and .223 ammunition?

To a layman, the 5.56mm. cartridge and the .223 cartridge are the same dimensions. However, many people would advice not to use one in a rifle that is designed for the other, so clearly there must be some differences. This post attempts to clear the mysteries.

First thing to note is that while the US military started switching to metric measurements in the 1950s, in order to better work with NATO military forces, the rest of the US still stayed on with English measurements to the present day. Therefore the US military calls the diameter of the bullet as 5.56 mm. whereas the civilian market calls it .223 caliber (i.e. 0.223 inches diameter), even though they are the same diameter. A good rule of thumb is to assume that when people refer to 5.56x45 mm. cartridge, they are talking about the military-specification cartridge and when they say .223 Remington, they're usually referring to the civilian version of the cartridge.

When it comes to cartridge dimensions, the 5.56x45 mm. NATO cartridge and the .223 Remington have almost identical dimensions. Note that the operative word here is "almost": they are similar enough in shape that either may fit into a gun designed for the other, except for those firearms designed to very tight tolerances. However, there are differences in the pressures and velocities generated by the two types of ammunition. For one thing, 5.56x45 mm. cartridge has thicker case walls. The .223 Remington cartridge also generates far less pressures compared to the 5.56x45 mm. cartridge. What this means is that it is generally safe to shoot .223 ammunition in a rifle designed for 5.56x45 mm. NATO cartridges. The reverse is not true though: firing 5.56x45 mm. ammo through a rifle designed for .223 ammunition may cause excessive stress to the rifle's barrel and chamber because the rifle is designed to operate with the lower pressures of .223 ammunition, which could lead to a very unsafe situation.

While firing .223 Remington cartridges through a rifle designed for 5.56x45 mm. ammunition is generally considered safe, the slight differences in cartridge dimensions make the rifle slightly less accurate than if the .223 Remington cartridges were to be fired by a rifle designed for .223 Remington.

Tuesday, September 4, 2012

Harmonica Gun/Slide Gun

In this post, we will look at a particular type of multi-shot firearm, the Harmonica Gun.

For centuries, many people were trying to build multi-shot firearms. For instance, there were pepperbox revolvers developed in the 1500s and the Colt Paterson revolver from 1836. Many of these early firearms had a 5 or 6 round capacity at most. In order to allow loading more rounds, some people developed the Harmonica Gun, otherwise called the Slide Gun.

It isn't exactly very clear who invented the first harmonica gun, but one of its early famous makers was Jonathan Browning, who started manufacturing them in Quincy, Illinois, way back in 1834. Jonathan Browning later migrated to Ogden, Utah and is mostly famous today, not for his harmonica guns, but for being the father of the famed firearm designer, John Moses Browning.

A harmonica gun. Click on image to enlarge. 
Image licensed under Creative Commons Attribution-Share Alike License 3.0 Unported by Amendola90 at Wikipedia

It consists of a firearm with a steel slide, which has multiple chambers bored into it. Each chamber is loaded with a cartridge, or with powder and ball. Firing mechanism is either via percussion cap or a pinfire cartridge, depending upon the manufacturer and model. The steel slide is loaded into a slot on the side of the firearm and locked into place using a cam or a spring loaded plunger.

Since the slide resembles the musical instrument, the harmonica, this type of firearm was called the harmonica gun.

In order to fire this weapon, the user simply cocks the hammer, then unlocks the slide's locking mechanism (cam or plunger) and moves it so that a new cartridge comes under the hammer, applies the slide lock and then pulls the trigger. The user needs to re-cock the hammer and move the slide manually each time to fire the next round.

Harmonica gun mechanisms were not restricted to handguns alone. For example, General Sam Houston was known to own a percussion rifle that used a harmonica loader mechanism and this rifle is displayed in the Smithsonian museum.

Harmonica Rifle owned by Gen. Sam Houston. Currently exhibited at the Smithsonian museum.
Click on image to enlarge.

Harmonica guns often held 9 or 10 rounds in a slide and definitely had more capacity than revolvers of that era. However, since the user needed to move the slide manually along with cocking the hammer, it took more time to prepare one for firing than a revolver-type firearm. Balance was also a problem, especially when firing the first few or last few rounds, because the slide would predominantly hang off one side of the firearm and affect its balance. Also, the user would have to disassemble the slide from the firearm before they could carry it in a holster, which meant that these could not be immediately brought into action like a revolver could. These are some of the reasons why harmonica guns never really sold well, because of the competition from reliable revolvers.