A Matter of Purpose: Striker Fire vs. Hammer Fire
ABOVE: A mix of various caliber centerfire ammunition surrounding .22 rimfire cartridges too small to accommodate a centerfire primer.
No matter what operating system a firearm employs, there are only two mechanisms used to fire metallic centerfire and rimfire cartridges; they are striker fire and hammer fire. Most people correctly associate a hammer-fired weapon with a revolver from Hollywood’s depiction of a cowboy cocking his revolver’s hammer fully back to its firing position. Less known are striker-fired firearms because the striker is hammerless and is concealed within the gun. The advantages and weaknesses between the two firing mechanisms have been the subject of a 100-year-old debate, with fans of each providing emotional reasons why their favorite is better; but is one functionally better than the other?
A technical understanding of how and why these two firing systems are used in a particular firearm design is important. For example, there are three basic autoloading operating systems used in modern autoloading firearms: gas impingement, gas piston and blowback (more on the operating systems in a future article). No matter which operating system is used, most autoloading rifles are hammer-fired while modern autoloading pistols, especially those designed for concealed carry, often use striker fire.
On the other hand, manually operated actions include bolt action, lever action, pump action and the break open hinged receiver. Bolt guns generally use striker fire while lever action, pump action and break open actions often use hammer fire.
Modern firearms all fire metallic-cased centerfire (to include shotgun shells) or rimfire cartridges offered in a variety of calibers. Both cartridge types must be struck on the primer-base end of the cartridge to be initiated. Center fire cartridges refer to the primer’s location being in the center bottom of the cartridge. Rimfire cartridges have the primer cast into the entire base of the cartridge and can be struck anywhere on the base to be fired. Rimfire is used on cartridges with a base diameter too small to contain a center fire primer (typically .22 caliber cartridges, but there are several others) and thus cannot be reloaded.
All firearm designs commonly employ a firing pin of sorts that strikes the cartridge’s primer (dimpling it), which in turn initiates the spark that ignites the propellant (smokeless gun powder) charge contained inside the cartridge case. Once the propellant charge is ignited by the primer, the propellant burns at high velocity (it does not explode contrary to popular belief). The propellant burn generates a predetermined level of pressure based upon the powder’s chemical formulation and quantity that propels the bullet (projectile) down the bore at a determined velocity to exit the gun barrel in stable ballistic flight on its way to the target.
So how does one determine whether a gun is hammer-fired or striker-fired and why does it matter?
Simply put, a hammer employs rotational energy to strike the cartridge primer. A striker uses linear energy to strike the cartridge primer. Both the hammer and the striker are propelled forward by a spring. Therefore, spring quality is a common key reliability factor to both hammer- and striker-fired firearms. Neither can operate without a spring to propel (power) it forward.
While some hammers are contained internally, or shrouded from outward appearance, they all pretty much work the same. When the trigger is pulled releasing the trigger sear, the hammer springs forward, either directly or indirectly, striking the firing pin which in turn strikes the cartridge primer, firing the weapon. Many older revolver designs with exposed hammers have the actual firing pin attached to the hammer. In more modern hammer-fired designs, the hammer has a flat face that strikes a firing pin, which subsequently strikes the primer and fires the cartridge.
In flat-face, hammer-fired designs that utilize a firing pin and striker-fired designs, there is a small internal spring that shrouds the firing pin housed inside the firing pin cavity. The purpose and importance of this small spring is to retract the firing pin backward from its extended firing position following each hammer strike. This small firing pin retraction spring prevents the firing pin tip from dragging across the next chambered cartridge and from accidentally firing it as the bolt/slide is closed or a revolver’s cylinder rotates. Thus, the firing pin retraction spring is a critical safety element in preventing misfire during bolt / slide / cylinder-cyclic operation. As such, they should be regularly checked for proper operation and replaced if the firing pin doesn’t fully retract.
A hammer fire’s disadvantage is the inherent delay caused by rotational travel of the hammer. While this delay is negligible, it is present, and its travel timing must be accounted for in automatic weapons. Secondly, in autoloading firearms like the AR, for example, the hammer is cocked by the bolt carrier group passing over it on the recoil back stroke. The opposing force of the hammer dragging on the base of the bolt carrier group causes wear if not lubricated. It can also slow the rate of fire or cause a failure to eject, or a failure to feed malfunction if not maintained and lubricated properly. In some blowback operating system designs, hammer drag is used to time the rate of fire by slowing the slide’s or bolt’s backstroke.
Carrying a hammer-fired weapon with the hammer down, the hammer spring is at rest–and not under tension in a condition one scenario. This may add a comfortability factor while carrying because it significantly reduces the probability of accidentally firing a round when drawing. On the other hand, it presents a disadvantage in the event you need to draw and fire your weapon quickly because the hammer must first be cocked to fire the gun. Or, if you’re using a double action gun, the first-shot trigger pull is much greater than the following shots and this greatly increases the chances of a first- or second-shot miss for less experienced shooters.
Why then do most military assault-style weapons and machine guns utilize hammer fire? The answer is subtle and little understood. Because the hammer rotates on axially and is powered by a spring, its mass can be made more robust (heavier) than a striker. Additionally, the fact that it springs forward on an axial pivot point allows its inertial travel momentum greater leverage and thus, a consistently harder strike upon the firing pin / primer. Therefore, the rotational operation of the hammer mass provides a more energetic primer strike.
A robust primer strike is important because military (MILSPEC) ammunition generally uses a harder primer which requires a harder firing pin strike to initiate than the primers used in the civilian counterpart. From a military perspective, a harder primer provides an additional degree of safety in rough handling combat scenarios and as such, it requires a harder firing pin strike to initiate. It is for this reason that the military generally prefers hammer-fired weapons. Some famous US military hammer-fired weapons include: Colt Model P “Peacemaker” revolver, Colt M1911 pistol, Beretta M9 pistol, M1 Garand, M14 rifle, M16 rifle, and M4 carbines.
Striker fire is a different ballgame; its primer-striking energy is linear. With less parts required than hammer-fired designs, striker fire is less complex, and less parts mean less weight, but not necessarily less maintenance or greater reliability.
Invented by Daniel LeFever in 1878, the first striker-fired weapon was a shotgun. Striker-fired designs differ from hammer-fired designs because in most applications, the striker is the actual component that strikes the cartridge primer and is often thought of as an elongated firing pin.
Here’s how a striker works: When the trigger is pulled and the trigger bar releases, the striker is propelled forward as its compressed power spring relaxes. This linear motion drives the striker forward to impact the chambered round’s primer, which subsequently fires the round. In some designs, the striker travels forward to impact with a firing pin (similar to a hammer strike), and in some designs, the striker and the firing pin are one.
Strikers are commonly used in many modern semi-automatic pistols, bolt-action weapons and shotguns. Even though Glock wasn’t the first to use striker fire on pistols, Glock can be credited for making the striker fire popular in the 1980s when they started using striker fire in their entire line of pistols. As Glock became popular, other manufacturers started using striker fire as well, proliferating it across the firearms manufacturing community on a grand scale.
It is important to remember, there are several striker-fire design variations employed by various firearm manufacturers used to tension the striker’s power spring. For example, in Springfield’s XD pistols and Smith & Wesson’s M&P models, the spring is fully tensioned as the round is chambered. Correspondingly, Glock partially tensions the spring until the trigger is pulled which increases the spring tension just prior to the striker’s release. These differences largely effect the trigger pull (feel) and little else. Today, striker fire can be found in Glock pistols, Smith & Wesson’s M&P models, Springfield’s XD line, Ruger’s SR9 and numerous other pistols, rifles and shotguns.
There are several benefits to striker-fired firearms, especially in concealed carry. Since there is no protruding external hammer, striker fire offers a more snag-free carry design. Secondly, each trigger pull, from the first through the final round of the magazine, has the same weight of pull (and feel) as compared to double-action/single-action hammer-fired designs (where the trigger pull force is different depending on whether the firearm is working in single-action or double-action mode). Third, most striker-fire designs lack an external safety. This means the operator can draw and fire upon an assailant(s) with fewer preparatory steps; for example, no need to manually disengage a safety or cock a hammer before firing.
There are some disadvantages to striker fire as well. When carried “hot” with a round chambered, the firearm is in condition one and ready to fire. Just pull the trigger. This can be a blessing or a curse depending upon one’s shooting experience. For those shooters who are comfortable on their draw, a striker-fired gun can significantly reduce the time from draw to first shot. For inexperienced shooters, it can lead to accidental discharge or unintended fire before the gun is on target and is a major safety issue. Last, dirt and sand can jam a striker if it enters the cavity containing the striker. This is a reliability issue that largely concerns the military that again has historically driven them to hammer-fire weapons over striker-fire designs. Note: That preference was debased in 2017 by the US Army’s decision to replace the service standard Beretta M-9 hammer-fired pistol with the SIG SAUER P320 striker-fired pistol (and they’re already having problems with the new pistol).
Find Your Operational Purpose
Most experienced shooters own several hammer-fired and striker-fired firearms. Some might say that one gun fits all requirements. That is simply not the case, especially for concealed carry, because the choice of gun you’re concealing should be consistent with the type of clothes you’re wearing—for example, shorts and T-shirt versus shirt, coat and slacks—as well as the level of shooting experience you maintain. Choosing a hammer- or striker-fired pistol comes down to purpose, personal preference and best feel. The same is true for long guns. Both designs offer advantages and disadvantages in safety, ergonomic feel, trigger pull and concealability.
The “which is better” argument between hammer fire and striker fire directly correlates to mindful firearm design to best achieve the firearm’s operational purpose. As you now know, both striker- and hammer-fire designs have technical and operational advantages and disadvantages. When one or the other is appropriately designed into a firearm, “better” quickly becomes the opponent of “good enough.” The bottom line is, identify the operational purpose of the firearm and get to know what works best for you before you buy. Don’t do it any other way. Your life might depend on it.