The omnipresent trigger on modern firearms is the key interface the operator has with his or her firearm, but most don’t really understand its importance. To properly address the trigger, let’s take a stroll down firearms memory lane and look at how triggers came to be — before we examine the all important interface.
We do know that in 1364, the metal hand cannon was developed, made, and adopted in Perugia, Italy. Those crazy, creative Italians are responsible for inventing so much cool stuff, aren’t they? Ferrari’s, Gina Lollobrigida, Sofia Loren… but I digress. I’m sure that the invention of the hand cannon must have went something like this: After a hard day of blowing stuff up and destroying castle walls with field cannons, Pasquale and his hommies are at the local bistro hammerin’ down some shooters… I know, but it’s a sickness that I have…
Anyway, Pasqua says, in Italian of course, but not to worry, I will translate… “Oh! man that was, like, so cool! Blowin’ stuff up today! But you know what would be really cool, like! If everybody had, like, their own cannon that was small enough that they could, like, carry it around and there would be, like, a thousand guys with 1,000, small cannons pointed anyplace they want instead of, like, 50 guys with only one cannon. Man that would be, like, sooo cool!” If you can’t tell he’s, like, a Valley guy.
Someone must have been listening, because as mentioned, the ‘hand gonne’ is credited as having been made in Perugia, Italy in 1364. Initially, however, it was not a great influence on the battlefield. It was a small man portable cannon with a touchhole (breach) for ignition. It was heavy, unwieldy, unsteady, and required that the user prop it on a stand. The user had to brace it with one hand against his chest, while trying to manipulate a lit rope (a slow match) with the tips of his fingers towards a touchhole on the barrel. Needless to say, the technique was extremely cumbersome, prone to inaccuracy, and not very efficient.
The first recorded use of a Hand Cannon in Europe is when it appeared on the field of battle during the reign of Edward III, where it only had an effective range of about 30 yards. It was a start, but clearly, something better was needed.
Trigger Time
As far as firing mechanisms go, the idea of using a trigger to activate a weapon was not a new invention, as they had been used in crossbows for centuries. It was only logical that the idea of the trigger should be adopted for firearms as well, and so the “Matchlock” was born. The Matchlock generally conforms to what a modern sporting rifle looks like.
Matchlocks have a wooded handle or stock that can be braced against the shoulder, aimed (really pointed) in the direction of the target, with a trigger protected by a guard. When the trigger was actuated, it moved the slow match that was held in a curved lever called a Serpentine or Cock to the touch hole to ignite the charge and fire the weapon. And so, the trigger was born as the principal actuator of a firearm.
It was so successful that matchlock technology stayed alive for a very long time. As a matter of fact, well into the 19th century, matchlock weapons were still being used in India, China, and Japan. There were even some records of rebels using matchlocks in East Timor well into the 20th century.
There were other improvements to the lock mechanisms, but in all of them, the trigger was only a release initiating the first action to occur. The next big leap in technology was the Flintlock. In the Flintlock, the pan holding the initial charge of powder is covered with a steel plate (a.k.a, the “frizzen”). When the trigger is pulled, it releases the hammer that falls under spring pressure to strike the frizzen. This action creates the sparks that initiate the firing sequence. So, the Flintlock’s trigger still functioned only as a release for the cock or hammer holding the flint.
Double Action
In 1835, Colonel Samuel Colt introduced the Paterson No. 1 Revolver with 5 chambers that rotated when the hammer was cocked to provide 5 shots on demand. As revolutionary as his invention was, the trigger was still single action and only released the hammer. However, things were about to change.
During the 1850s, another mechanism called the “Double Action” was invented. The inventor was Robert Adams, and he invented a revolver where pulling the trigger cocked the hammer, rotated the cylinder, and then released the hammer — all with a single (all be it longer) trigger pull. This means, it also has a harder trigger pull than a single-action revolver, much like the Colt and Smith & Wesson products of that period. On the other hand, the rate of fire was much higher than a single-action revolver, because the user doesn’t need to cock the hammer separately before pulling the trigger. The Adams revolver was a percussion cap firing mechanism, and the cylinder had 5 chambers in it.
What we just learned is that a single-action trigger is inherently lighter, requiring less force and movement to operate than a double-action trigger. This happens because the double action has a longer distance to move, more weight, and more resistance to overcome. And so, the appearance of the new, improved models of double action that could be operated in both single- or double-action mode was such a huge success that Samuel Colt had to shut down his factory in England. With that development, it came to be that mechanisms operating in both single- and double-action mode are called DA revolvers (DA standing for “double action”).
Trigger Pull
The term that defines the amount of force that is needed to cause the trigger to release in a firearm is referred to as “trigger pull.” If a firearm has a very light trigger pull (a.k.a. a hair trigger), it takes very little force to activate the trigger. Hair triggers are found on single actions because all the resistance to stage the firearm for firing has been accomplished by the shooter’s strength when “cocking” the mechanism.
The shooter either rotated the cylinder of a revolver by cocking the hammer or cycled the slide on a single-action pistol. On a bolt-action rifle, the bolt is cycled. On a lever-action, the lever is operated. The trigger pull weight on a single action can be as light as 2 ounces. Be advised, a trigger that is light also has a greater chance of accidentally discharging, for all the same reasons.
On the other hand, if a firearm has a heavy trigger pull, the user will not be able to shoot as rapidly or as accurately. This happens because the force required to pull the trigger will usually cause the user to shake, making the firearm move a bit more and be more difficult to hold on target. Most single-action triggers are normally set from 4 to 7 pounds.
Single- and Double-Stage Triggers
When we talk about rifle triggers, the first two that come to mind are the Single- and Double-Stage (2-stage) triggers. There is also the lesser used Set Trigger, in both single- and double-set, which we will cover later. The differences between the first two trigger types are minor but can make a significant impact on your performance.
It’s important to remember these differences, because as stated earlier, the trigger is the primary interface that connects you to your gun. Pressing the trigger is the last human action before the mechanics of your weapon take over. That said, both types of triggers work well in multiple applications, and it’s up to the individual shooter to choose which one works best for them. They’re both capable of accuracy and speed.
Users of both types must familiarize themselves with the feel of the triggers before they can use them confidently. I use all three types of triggers and find they each excel at different shooting tasks. Whichever type of trigger you choose, so long as you are safe, accurate, and enjoy your time behind your rifle, you have selected the correct one. Keep in mind that the placement and design of the single-stage and double-stage triggers are not discernible to the eye. They’re located within the trigger guard, and their appearances are similar.
Single-Stage Triggers
Let’s start by looking at the single-stage trigger first. Today, most bolt-action sporting rifles come standard with a single-stage trigger. A single-stage trigger is designed to release the sear and fire the gun as soon as the trigger finger exerts enough pressure to release the sear. Single-stage triggers do not have a change in weight throughout the pull. Ideally, there is no slack, creep, take-up, or over travel with a single-stage trigger. This means that the once the sear is released, the trigger will not travel any further. Single-stage triggers are a bit more complex, but they can be adjusted to an individual shooter’s preference.
Double-Stage Triggers
Most shooters are familiar with double- or 2-stage triggers, because they have been traditionally encountered on military rifles such as the Mauser, 1903 Springfield, and M1 Garand and Carbine. 2-stage triggers have a slightly different operating process. It has two firing phases that allow the shooter more control over when the shot will be fired.
With a double stage, there is slack, creep, or take-up when the trigger is initially moved rearward, and then, resistance is felt. This resistance is where the additional force is needed for the trigger to release the sear and fire the gun. The first phase doesn’t fire the gun, but provides safety from accidental discharge. Once you continue to press, after the initial resistance or wall is encountered, the trigger break is instant, and the weapon will fire. Having control over the exact time your trigger will break can enhance your accuracy.
Additionally, when the shooter applies his initial pressure to the trigger, he or she can pause midway without firing the shot. If the shooter decides to release the pressure on the trigger, the trigger will reset to its original position, and the shooter can start over. If you wish to proceed with the shot, just add a little more pressure and the rifle will fire.
Another thing to consider is that two-stage triggers are also less prone to accidental discharge when dropped, compared to single-stage triggers. This is due to the wall that is encountered before the trigger breaks. Both triggers are excellent. The final decision comes down to your personal preference. The only way to find out which trigger works best for you is to try both. That way, you can determine how each works for you and the type of shooting you do.
Set Triggers
Double Set Triggers
The next type of triggers are called Set Triggers. There are double set and single set. The double set has been around since black powder days. Although it has a long history, we do not see it employed much today, except on some European brands. On a rifle with Double set triggers, one sees two triggers — one in front of the other. The front trigger operates as a normal trigger — unless the rear trigger is squeezed first to “set” it.
The rear trigger is a complete secondary, miniature action. When cocked, by pulling the rear trigger, the action transforms the front trigger to a hair trigger. When the front trigger is then pressed, a spring powers a miniature hammer. This multiplies the force of the front trigger’s pull, allowing a very light touch to accomplish the release of the main sear.
While the front trigger is always at the ready (requiring a 4-pound pull), if one has the time, using the set trigger feature may allow for a more accurate long-distance shot because now the trigger requires only a 4-ounce pull. To use this feature, the rear trigger must be deliberately pulled, just prior to taking the shot. It would be dangerous to walk around with a rifle having a 4-ounce trigger as standard. To distinguish a double-set trigger from double triggers, it is recognizable by the small setscrew used to adjust the weight of pull. That, and the fact that the rifle will only have one barrel. Those are the giveaways.
Single Set Triggers
The next type of set trigger is the single-set trigger. The one I will describe was very popular from about the mid 1950s through 1990 when. Mr. Canjar passed. I have several Canjar Triggers. They are arguably the best trigger any rifle can have. His was a single trigger that would be set with a normal pull weight of say 4 pounds. When the trigger is pushed forward, a small lever in the center of the trigger protrudes. When that is touched, the rifle fires. Mine are set to 2 ounces.
Hammers and Strikers
Today, most modern pistols use one of two types of mechanisms to ignite the cartridge primer. One uses a hammer and another a striker. The ones that use a hammer are called ‘hammer fired.’ The ones that utilize a striker are called ‘striker fired.’ With the hammer-fired mechanism, the hammer is a heavy piece of metal that rotates around a pivot point.
When the hammer is cocked, a spring is compressed. When the trigger is pressed, the hammer is released. The spring propels the hammer, it rotates forward and strikes the back end of a firing pin. In turn, this strikes the primer of the cartridge, detonating it. In some revolvers, the firing pin is attached to the hammer.
In contrast to hammer-fired mechanisms, striker-fired systems operate in linear fashion. The striker is similar to a firing pin, but it is somewhat heavier and directly connected to a spring. When the firearm is cocked, the striker is moved against the spring and locks it in a position where the spring is only under partial tension and held in position.
Pulling the trigger compresses the spring before it releases the striker. The spring forces the striker forward with enough energy to fire the pistol. Because of that, the trigger pull is heavier with the striker system than that required with a single action.
Striker-fired mechanisms tend to have fewer parts than hammer fired mechanisms. Striker-fired systems are simpler. However, they take up a bit more room. This simplicity and ease of manufacture is why we see them used in so many new designs, they are not better, but they are cheaper.
Many people believe, incorrectly, that Gaston Glock invented the striker-fire mechanism, but he did not. In fact, the first striker-fired weapon invented was a shotgun invented by Daniel LeFever in 1878. That said, striker-fired pistols became popular in the 1980s, when Glock popularized them.
Some favor the striker-fired mechanism. They claim it does not have an exposed hammer to get caught on clothing. However, should you have a malfunction with a striker-fired weapon due to a bad primer, your only option is to eject the cartridge and try the next one. Hammer-fired guns generally impact primers harder than strikers do, providing more reliable detonation. I also eschew striker-fired guns because most do not have a manual safety. That is an accident waiting to happen and more often than not, it does.
I hope this provides some useful information to help guide you in your search for the right trigger. Stay safe, train often and practice, practice, practice!
What’s your take on triggers? Do you prefer hammer- or striker-fired pistols? Single- or double-stage triggers for rifles and why? Share your answers in the Comment section.
A cased Colt Paterson revolver. Early ‘hand gonne’ shown deployed by cavalry and infantry. 
The “Matchlock” at the moment of ignition. The “Flintlock” with all its key parts labeled. A Colt Single Action Army revolver showing the positions of the trigger as the hammer movement compresses the springs and stages the action for firing. The first image shows the action at rest. The second shows the positions at “half-cock.” The third image shows the revolver cocked and ready to fire. Notice the position of the trigger is only slightly forward of its ‘at rest’ position indicating a very light press would be necessary to trip the trigger. The Glock pistol with its — I use the term loosely — “Safe Action Trigger” in both the uncocked and cocked position. The only safety is the little lever protruding from the center of the trigger. It needs only to be depressed — by anything — for the pistol to fire. These images show the Canjar Single Set Trigger in its various positions. From left to right: 1. Action uncocked. 2. Action cocked 3. Action cocked trigger at standard pull. 4. Trigger “Set” for 2-ounce press. Notice the lever in the center protruding, that is the “Set” trigger. On the left is a double-set trigger, notice the adjustment screw between the triggers that indicates this is a Set Trigger. By contrast the set on the right is a double trigger for a rifle or shotgun with two separate locks and barrels. 
A Walther PPK/s pistol showing the position of the trigger for the longer, harder, double-action pull or the short, light, single-action position press. Here is a Smith & Wesson double-action revolver showing the position of the trigger for the longer, harder, double-action pull or the short, light, single-action position. 
Here is a Colt 1911 single-action pistol. Notice the trigger has imperceptibly moved from at rest to its fire position, indicating a very light trigger.
Gotta love these historical articles from Ed.
I came to the comments for what JENS said above, “I still don’t get the flat trigger.”
I get a sense it’s pure marketing garbage… some people will believe (then buy) almost anything.
I mean, there’s literally commercials for body paste deoderant that suggest you no longer should rely on soap and water. But I digress….
I didn’t see any discussion about release triggers…
Excellent explanation of the trigger mechanism. Ed deservers a A+++ for this article. I am not a fan of
the two stage trigger with slack/creep before hitting the wall. In fact, I will not buy a firearm with that feature. Just my preference. .One more note, I prefer a trigger pull of less than 4 lbs. I am merely a target shooter so I understand that others may like different triggers for shooting game.
I really liked the Article on Types of Triggers but What about the latest type of Trigger being talked about here and there and that would be Binary Triggers. any information on these particular type Triggers as far their use and how they operate?
I still don’t get the flat trigger. Our fingers are round (curvy) which leads me to believe a more repeatable pull with a curved trigger.
I believe the best of both worlds is a double/single action on a semi auto.
I hope CZ brings the lightweight RAMI back. My CZ 75 compact is superb, but the smaller RAMI would be better for Concealed Carry.
Thanks Ed! That was quite a Fun History Lesson on trigger types.
I can think of another trigger type somewhat exclusive to Bolt Action Action Rifles and that one is the Manual Cocking type, mostly seen on beginners or introductory rimfires.
I once owned a Single Shot, Bolt Action 22 called the “Humdinger” that I’d purchased at B & B Gun Sales
On Oxnard in No. Ho.
It featured a Knob at the rear of the bolt which needed to be manually pulled to the rear upon closing the bolt in order to cock the rifle for each shot. I thought it a rather clever method for teaching beginning shooters the safety protocols and also meant that the rifle could be stored or carried with a round in the chamber but not cocked and thus pretty safe in case of dropping.
As a side note. I think that Pasqua lived in the “Alps” above Ventura blvd near Woodley ave. “Fer Shur”!
Another fantastic article written by Ed LaPorta . You’re truly an asset to the firearms industry campaign.