The Failure to Eject
In a failure to eject type of malfunction, the fired cartridge case is extracted from the chamber. However, it does not get ejected with enough force to clear the ejection port. The base remains partially in the gun, getting captured between the bolt face and the chamber mouth.
One of the reasons for this happening is a light load that does not allow the slide to travel its complete length, coupled with the lack of ejection force strength. Those factors contribute to the shell case not being able to clear the ejection port. The slide then moves forward with the shell case pressed against the bolt face. Because of this, the slide cannot close, and the gun gets jammed.
The Stovepipe Jam
Note that in the accompanying image of a typical stovepipe jam, an empty cartridge case is stuck in the ejection port, sticking out the top of the pistol. This is an example of a classic 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 sticking out above a roof line.
A stovepipe jam usually occurs in semi-automatic or fully-automatic firearms. It is a failure-to-eject type of malfunction where the cartridge that was just fired did not get ejected from the firearm properly and is partially stuck in the ejection port. This means the weapon cannot load the next cartridge into the chamber properly and will not fire.
What causes a stovepipe?
There are four main causes contributing to stovepipe jams. The first type being what is referred to as limp wristing the weapon, or not holding the firearm firmly enough to offer the required amount of resistance and rigidity against the recoil forces of the firearm. Because of that lack of resistance to the firing action, the recoil forces may not complete their cycle properly and a jam occurs. This is more commonly seen when using handguns as opposed to long guns, which are supported against a more rigid shoulder.
Old, lightly loaded, or bad ammunition can also be a culprit. The propellant in the cartridge case may have degraded due to age, or the case may not have been filled with enough propellant which can both be causes. Either way, the burning propellant doesn’t generate enough power to cycle the action properly, so the cartridge doesn’t get fully ejected by the time the slide starts its return back into battery.
A bad or damaged ejection mechanism can also create the problem. Either the return spring of the slide may be too strong, or the extractor or extractor spring that extracts the old cartridge is too weak and does not allow the ejector to do its job. In either case, the slide moves back, until it gets pushed forward. The slide starts to close before the old case is fully ejected. Therefore, the old case gets caught before it has a chance to fully leave the firearm.
The ricochet is when the fired case does get ejected, but it hits something on the way out (e.g. 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 from that when configured with a snail-drum magazine that fed from the left hand side. It did not exhibit this issue when configured with a box magazine fed from the right hand side.
Clearing a Stovepipe
As can be seen clearly in the picture above, the empty cartridge case was not fully ejected out of the firearm. The case became caught between the slide and the hood of the chamber, preventing it from closing fully. Therefore, the pistol jammed. Fortunately, stovepipe jams are relatively easy to clear, without using any tools.
To clear a stovepipe, simply use your weak-side hand to sweep over the top of the slide — front to rear with authority. That action will displace the case. The force of the mainspring will force the gun into battery with a fresh cartridge ready to be fired. As stated, the primary cause of this problem, in handguns, is cause by limp-wristing. However, if the problem continues to happen, the extractor, ejection spring, or return spring (or more than one of the above) may need to be replaced.
The Slamfire Malfunction
Another type of malfunction is the slamfire. When a new cartridge is being loaded into the chamber of the firearm, sometimes the bolt slams the cartridge into the chamber with such force that the weapon fires without the user having pulled the trigger. This is known as a “slamfire.”
A slamfire is particularly dangerous because it happens when the user is usually not expecting. In some firearms, it can happen when the user’s finger is off the trigger. In the case of semi-automatic weapons, it may cause them to keep firing until the magazine is empty. Since a slamfire comes as a surprise to the user, it can cause the user to lose control of the firearm and point it in an unsafe direction.
Slamfires are a more common occurrence in weapons that have a free-floating firing pin, than in weapons that have a spring-loaded firing pin. When a semi-automatic or an automatic firearm is fired, the hammer strikes the firing pin, which then moves forward to strike the primer. This sets off the chain of events that forces the bullet to exit the barrel.
Some of the resulting recoil force is harnessed to cycle the reload procedure of the firearm automatically. The recoil force pushes the bolt backward. As it moves back, an extractor claw pulls out the cartridge that was just fired. The bolt continues to move backward and compresses the main spring. Meanwhile, the extractor claw pulls the empty cartridge case backward, until it can be pushed out via the ejection port.
Meanwhile, the bolt moves to its backward most point until its momentum is overcome by the compression of the main spring. The cartridge case is then pushed forward again by the force of that return spring. On its way forward, the bolt face picks up a new cartridge from the magazine and pushes it into the chamber.
As the bolt reaches the chamber, the firing pin continues to move forward due to inertia, until it is stopped by the cartridge’s primer. Now, if the firing pin is spring loaded, the spring slows down the firing pin, so it does not slam against the cartridge’s primer hard enough to ignite it. However, if the firing pin is free-floating, there is nothing to slow it down as it slams into the cartridge’s primer.
In either case (but especially for free-floating pins), there is a chance that the firing pin slams into the cartridge primer a little harder than expected and could cause it to detonate prematurely. This causes the firearm to discharge without the user pulling the trigger causing the slamfire where the cycle can repeat.
Free-floating firing pins are more common with military firearms, so there is a greater chance of slamfires occurring with them. Of course, this is not to say that firearms with spring-loaded firing pins are immune to slamfires, because it can happen with them as well. However, it is not as likely as guns with free-floating pins.
Slamfires can also happen on some bolt-action firearms when the user is manually cycling the bolt and pushes it forward a little too hard. Some of the causes for slamfires may also be dirt or corrosion. If enough dirt gets in the bolt’s firing pin channel, it could cause the firing pin to stick to the bolt wall and protrude out of the bolt. This could cause a slamfire.
The same thing could happen if corrosion causes the firing pin to protrude out of the bolt. Ammunition could also be at fault. Some ammunition is manufactured with more sensitive primers than others and require less force to detonate, and that could cause slamfires.
Preventing a Slamfire
The solutions to fix those causes are as simple as keeping your firearm clean to prevent dirt from jamming the firing pin and ensuring to use cartridges with less sensitive primers, so more force is needed to detonate them. This is why military cartridges usually have harder primers, so they need an actual hammer strike on the firing pin, rather than inertia, to detonate.
Another solution is to use firearms that are designed to minimize slamfires. For instance, the firing pin should have a spring around it, so that it slows down the firing pin as the bolt slams forward. The spring provides enough resistance that the pin will not hit the primer hard enough due to inertia, but will detonate the cartridge when the back of the firing pin is struck by the hammer. Another field fix is to make the firing pin as light as possible. In that way it doesn’t transfer enough force to detonate the primer due to inertia.
Some models of firearms are more susceptible to this problem than others. If this is a concern, do some research into the design of a firearm before you purchase it.
Have you experienced a stovepipe malfunction? What was the cause? Do you regularly train to clear malfunctions? Share your answers in the comment section.