This article is an overview of some of the more common springs used in firearms.
Springs are critical to the function of nearly every firearm in existence. They are so critical that it is fair to say -- if the springs in your weapon are not functioning properly, your weapon is not functioning properly.
While not all firearms operate in the same way, there are some common design elements that apply to a wide range of weapons. For this discussion we will consider the following types of springs: hammer/striker, trigger reset, recoil, extractor, and magazine. These are not the only critical springs in firearms, but rather they are the ones that tend to give the most trouble in the field.
Hammer/Striker Springs provide the energy to fire the primer. They do this by aggressively denting the primer cup and firing off the primer charge. The difference between a hammer and striker spring is how they manage to dent the primer. A hammer spring typically drives a hammer into a firing pin which then dents the primer. In the case of a striker spring, the spring drives the firing pin directly into the primer. However it happens, the result is the same. The primer is dented and the round fires.
Very often, hammer and striker springs are replaced with lighter ones in order to reduce trigger pull. Unfortunately, while this may improve trigger pull, it adversely affects the ability of the weapon to ignite a primer. If a hammer/striker spring is weak or underpowered it may not strike the primer with enough force to ignite it. Quite a few things can work against a primer being ignited. A primer may have a metal cup that is thicker or harder than typical. In such a case it needs to be struck with more force to set it off. If the primer legs are not fully seated against the primer pocket it may move slightly when it is stuck and prevent the primer from being properly fired. Water, oil, or dirt can slow the firing pin enough that it doesn’t have adequite force to fire the round. Because the strength of the spring may have to overcome these other factors, it is critical to have full-strength hammer/striker springs in any serious use weapon.
The Trigger Reset Spring tends to be ones of those parts that is often ignored. Its purpose is to return the trigger back to the pre-firing position as you release the trigger. These springs are sometimes changed to adjust trigger pull, but don’t generally affect reliability of the weapon. However, if the trigger return spring fails entirely and the trigger doesn’t reset the weapon is rendered nearly or even completely inoperable.
The Recoil Spring applies to self-loading firearms and is not present in firearms such as revolvers or single shot rifles. This is the spring that slows the recoiling assembly of the firearm and returns that assembly back into battery after firing. It is generally the largest spring in a weapon. If this spring is too weak the recoiling assembly may batter the frame of the firearm and cause cracking. Or it may lack the power to bring the weapon fully back into battery when it is dirty or otherwise fouled. Another problem that can occur with recoil springs is if they are too light, the friction from a fully loaded magazine may also prevent them from going into battery. On the other hand, a recoil spring that is too strong may cause the weapon to short-stroke and cause stove-pipes or other types of jams. It may also cause short-stroking when firing one handed or when the weapon is dirty. As you can see, the proper-weight recoil spring is critical to proper operation. Either too weak or too strong a spring will cause reliability issues.
Extractor Springs come in an extremely wide range of shapes and designs, but they all serve the purpose of actuating the extractor so that spent shell casings are dislodged from the chamber of the weapon. While most all auto-loading firearms employ a spring-powered extractor, some firearms (such as most revolvers) rely on a manual extractor and will not have such a spring. However, with autoloaders the extractor spring is essential to the operation of the firearm. If this spring is too weak the weapon will experience failures to extract and often exhibit an irregular ejection pattern. If this spring is too strong the weapon may have trouble going into battery when it is not perfectly clean.
Magazine Springs do the job of moving the next cartridge into position just as the firearm reaches the fully open position. Because the recoil process happens so quickly, the next round must be moved into position without any delay. A weak or worn magazine spring can cause a wide range of malfunctions. In some firearms, a weak magazine spring will cause a nose-dive and in some instances it can cause the weapon to completely fail to pick up the next round. In such a case, the weapon cycles and appears to be functioning normally until you pull the trigger and realize there is no round in the chamber – not a good situation! On the other hand, if a magazine spring is overly stiff, it can cause failure of the feed lips, or slow the slide down so much that it fails to function properly.
As you can see from the above descriptions, springs are integral to the proper operation of most firearms. So, if you want your weapon to function correctly, include inspection of springs as part of your regular preventative maintenance checks and services.