Troubleshooting Firearm Malfunctions
Eight Functions of a Firearm
Before troubleshooting firearm malfunctions, it’s important to understand the eight functions of a firearm.
Feeding occurs when a cartridge moves into place against a bolt.
Chambering occurs when the cartridge moves into the chamber.
Locking occurs when the bolt, breech face, or cylinder is locked into position with the barrel.
Cocking occurs when the sear engages the hammer/striker is engaged. This can happen in conjunction with other functions in different types of firearms.
Firing occurs when the firing pin/striker hits the primer and ignites the powder to send the projectile through the barrel.
Unlocking occurs when the bolt or breech face unseats the case from the chamber. In some firearms, this is a manual process.
Extraction occurs when the extractor pulls the case from the chamber. In some firearms, this is a manual process.
Ejection occurs when the case is expelled from the firearm using the ejector. In some firearms, this is a manual process.
Typically, gun repairs fall into one of three categories: Extraction/Ejection issues, Firing issues, and Feeding/Chambering issues.
Extraction/Ejection Repairs
The most common issues we encounter are extraction or ejection issues. Most people think these functions are the same thing, but they differ slightly. On many guns, the extractor removes the fired case from the chamber while the ejector expels the spent cartridge from the firearm. Because this function is usually powered by the explosion (rather than the user), the motion of these actions is violent and forceful causing the gun to break or wear overtime.
Often, the fix is as simple as ordering and replacing either the extractor or the ejector. On ARs or shotguns, extraction/ejection issues can occur from a problem with a piston or gas systems. Other times, the gun can have issues with the chamber. For example, rust or scratches on the chamber could cause the brass to get stuck. This issue is fixed by removing rust and polishing the chamber.
Firing Repairs
Firing issues are the second most common gun repair we perform, and almost always it’s a problem with the firing pin. In some instances, it could be a problem with the hammer as well. Because the hammer hits the firing pin every time the gun is shot (on most guns), both the hammer and the firing pin endure a lot of force and wear over time.
We usually order firing pins, but if the part is sold out or is too expensive (like on a Browning Citori), we will make one on the lathe instead. It takes about fifteen minutes to turn tool steel on the lathe into a firing pin. After machining the steel, we have to harden and temper the firing pin.
We heat it up and quench it and leave it in a pot of molten lead for twenty minutes to temper. Using a temperature control unit (or PID) similar to the one we used for our electric bluing tanks, we can temper the firing pin with controlled heat of more than 600 degrees. We actually built the PID to control the temperature in the Cerakote oven we built back when the shop was our garage.
Feeding/Chambering Repairs
Feed and chambering issues are the third most common gun repair we perform. Feeding and chambering are often complex processes which can go wrong if something is just a little off. For example, shotguns can have loose or broken shell stops. Magazines can have bent parts. Deflectors—which are metal parts in the action enabling the round to fall into place—can be broken or bent. The front face of a chamber can be deformed which prevents a round from entering. The list could go on, and because so many thing could go wrong, these gun repairs often have more diagnosis involved.
