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I have a confession to make. When I got started with my first build, I spent an unhealthy amount of time trying to pick out my first AR-15 trigger. After months of buying everything else on the rifle, the trigger was the last bit. It was a Geissele SSA that I still use.

But, you know what, that was a bad call.

Bottom Line Up Front

If you’re new to shooting, or you’re building your first AR-15, I implore you to stick with the standard single-stage trigger. If you’re building, check out either the BCM PNT, ALG ACT, or ALG QMS. I linked to my preferred triggers down below.

The classic triggers smooth out over time. When you’ve finally burned out your first barrel in pursuit of marksmanship excellence, feel free to upgrade the trigger to give you that next step. Until then, jumping right to a high dollar trigger might shortcut your learning process.

Ok, moving on.

Triggers.

Next to barrels, AR-15 trigger selection is the most contentious issue for enthusiasts. It’s actually frustrating, because so much of it is personal preference, yet everyone will tell you unequivocally that you should get whatever model they like.

This article is less about me telling you what trigger to buy, and more about considerations between a single stage or two-stage trigger. I’ll throw some of my favorites in the mix, but realize they are purely my preference based on what I’ve had access to. There are a lot of AR-15 triggers out there to choose from, and more pop up every day. I simply don’t have the resources to test them all.

Philosophy Review

Before we get into it, I want to go back over the key points I laid out for buying anything. If you haven’t read it, I suggest going back to look at my article on selecting your first AR-15.

  • Let the mission drive configuration
  • Buy Nice or Buy Twice

Buy your AR-15 trigger and accessories based upon your actual needs. Avoid buying things for imaginary scenarios you will never face. And especially don’t buy something because they people of the internet would think well of it.

When you do make your selection, make sure you’re buying something quality. I don’t like call-outs, but I’m going to put one here. For many years back in the 2010 timeframe, the Rock River NM two-stage trigger got very popular as a budget option. Yet there were stories everywhere of them wearing out in only a few thousand rounds.

Inevitably, people would replace them with another of the same model. For the cost of two of them, they could have bought a single quality trigger that lasted longer than the rifle itself.

Trigger Terminology

Let’s get some terms out of the way so we’re on the same page.

A basic breakdown of the AR-15 trigger mechanism
A basic breakdown of the AR-15 trigger mechanism
  • Trigger – The portion that your finger squeezes during the firing cycle
  • Hammer – The portion under the most spring tension; it’s held in place by the sear until the trigger moves out of the way. Once released, spring tension drives the hammer’s mass into the firing pin of the bolt
  • Sear – The area where the trigger and hammer interface. When at rest, the tension of the cocked hammer rests on this area and keeps the weapon from firing.
  • Disconnector – As the weapon fires, the bolt carrier moves rearward and rotates the hammer back towards the cocked position; this process is extremely fast and the disconnector “catches” the hammer so that it does not go forward again
  • Hook – A portion of the hammer that the disconnector “catches” during weapon cycle. After cycling and the trigger is “reset”, the disconnector lets go of the hook and the trigger will re-engage the sear

Single Stage vs Two-Stage AR-15 Triggers

AR-15 triggers
One of my spare BCM single stage trigger units next to my Geissele SD-E two-stage trigger

There is a trigger suited to just about any need you might have. The vast majority of rifle triggers fall into one of two categories: single stage and two-stage. Within these categories, there is a variety of weights, trigger shapes, and materials.

There’s been a rise of things like binary triggers that fire on trigger squeeze and release, but you should treat them like the gimmicks they are. 

Single Stage Triggers

Single stage triggers are the most common type of AR-15 trigger on the market.

Nearly every issued M16 or M4 has a single stage trigger. The vast majority of rifles sold on the civilian market come equipped with a basic mil-spec-ish single stage trigger.

They are everywhere.

That doesn’t mean that the single stage is bad. There a many precision and hunting rifles on the market with this type of trigger.

A standard single stage trigger unit from Bravo Company USA

In fact, the M16 is the only combat rifle in the recent history to have a single stage trigger. Up until the M16, they were seen as precision triggers more than combat triggers.

A single stage trigger is basic. There is no or very little slack during the take-up. The full weight of the trigger is already resting on the spring and sear. To fire, the shooter simply overcomes that initial weight.

The trigger engages with the sear. If there is a lot of surface engagement, it feels heavier. The shooter has to “walk” through the sear engagement until it finally releases the hammer. This slight movement as the sear is disengaging is commonly called “creep.”

The standard single-stage trigger hammer. Note the notch at the bottom, the sear.

The distinct click you feel when you reset a trigger after each shot is the disconnector letting go of the hammer hook and the sear reengaging for the next shot.

Uses of the Single Stage Trigger

Common hunting and precision rifles in the bolt gun world use single stage triggers with light pulls of 4 lbs or less. In order to achieve a crisp trigger pull, there must be a minimum amount of sear engagement.

The surfaces are usually polished so that the little engagement there is gets smoothly released as the trigger moves.

The M16 designers thought a light/crisp pull was too dangerous for a combat rifle likely to get bumped around and mishandled by the average GI. To compensate, they raised the pull weight to a range of 5.5 to 8.5 lbs with a healthy amount of sear engagement.

Single stage triggers are popular due to their quick operation and simple design. All things being equal, a good shooter can probably shoot slightly faster with a single stage trigger. A light/crisp model can be designed to operate safely, but it will add to the cost of the unit. This cost is why a quality single stage is so much more expensive than the standard mil-spec trigger.

Two Stage Triggers

Geissele Super Dynamic-Enhanced (SD-E) two-stage trigger, characterized by the flat trigger bow

You know a two-stage trigger by its short and light initial take-up.  This movement is not the same as “creep.” Once you pull through the initial take-up, you reach a slightly heavier “wall” to overcome before the shot breaks. This is very similar to a DA/SA pistol with the hammer already cocked for single action mode.

The total weight of the trigger is the sum of both portions of the trigger pull. For instance, a 4.5 lb trigger might have a light 2 lb uptake followed by an additional 2.5 lb  “wall.” This provides a bit of safety slack for the rifle to be bumped around as well as a very predictable breakpoint for the shot. Every mainline combat rifle issued in the US military since WWI used a two-stage trigger.

The M16 was the first to break that tradition.

Another benefit of the two-stage trigger is the ability to “prep” it. The shooter looks through the sights, takes the initial slack out of the trigger and rides on the wall. Once ready for the shot, the shooter only needs to gently pull past the remaining wall to fire.

AR-15 two-stage trigger Geissele SD-E
On this two-stage trigger, notice the different shape of the hammer. The hook is double-sided, with one side facing the disconnector and the other is the sear. You might also notice that Geissele leaves the original sear at the bottom of the hammer as a kind of safety catch in case the main sear slips off. 

Double Stage Trigger Safety

There is a downside to the “prepping” method. With a light second stage, it’s very easy for a momentary lapse of focus to cause a premature shot. I’ve missed my target many times during practice because of this. That was during a relatively calm day on the flat range practicing marksmanship. More stressful situations with a too-light trigger might result in unintentional discharges.

Compared to a single stage trigger of the same weight, a two stage trigger will feel lighter. This happens because of the different spring tensions. On a 3.5 lb trigger, you will pull through the first 2 lbs during the take up and feel a notable, but very light, 1.5 lb wall before the shot breaks. In contrast, with a single stage trigger, you will feel all 3.5 lbs up front with no movement (ideally), and then the shot will break.

Tips For Selecting an AR-15 Trigger

This decision is purely personal preference. There are a wide variety of triggers on the market catering to different uses. Just remember that you get what you pay for. I’ve seen many inexpensive two-stage triggers from a well-known company fail within a few thousand rounds due to soft case hardening wearing through.

AR-15 Single stage hammer on the left and a two-stage hammer on the right

In contrast, triggers like those from Geissele, Wilson, or Laue Tactical have both an excellent feel and reliability record. Do your homework ahead of time.

Remember, everything is a compromise. Extra crisp triggers require extra time in machining and tighter QC tolerances, which mean higher cost. Super light triggers work great for target shooting competitions, a shooter under stress might inadvertently fire it.

I couldn’t get a nice pretty box like the one above, but if you’re on a budget then I highly suggest checking out the LaRue Tactical MBT. They often go on sale for less than $100, and it’s been another fantastic trigger for me. 

Or, even worse, poorly designed light triggers may release if the rifle is bumped or dropped. That’s definitely something you don’t want.

Materials and Reliability

No article about triggers is complete without some key points to look for in a trigger.

Material and Machining Process

The government standard for the M16 fire control group is an investment casting of AISI 8620 steel. For the hammer, AISI 4620 steel is also allowed. 

The differences between those steel blends aren’t that important. 4620 has a bit more nickel while 8260 has more manganese. Both are good strong steel alloys suitable for casting.

The important thing here is that mil-spec triggers are investment cast. This is a very old method producing complicated metal parts at scale. It is a different process from metal injection molding (MIM). 

Several manufacturers use other materials. For example, LaRue Tactical and Timney both make triggers out of S7 tool steel. As far as I can tell, that’s also a great option.

The bottom line here is that there are a lot of options out there, so do your homework and buy from a quality manufacturer. A well made trigger will last you a long time.

BCM ACT AR-15 trigger
BCM ACT trigger in my “Minuteman” rifle

Spring Weight

Some people like to use lighter hammer springs in their rifles. This reduces the tension on the sear. I suggest against anything less than a full power mil-spec hammer spring.

When Bill Geissele was just getting started, his first trigger was the Hi-Speed National Match. While at a match and partnered up with someone from the Army Marksmanship Unit, he and his trigger caught their attention. 

He was talking to the on-site commander at the AMU trailer and they were asking about his trigger. They were happy to learn that it used full power springs. The experience of the AMU, and many other military units, is that light hammer springs led to inconsistent accuracy. It usually showed up as vertical stringing of shot groups.

The same applies to bolt action rifles with reduced power striker springs.

Just something to keep in mind.

Wrapping Up on AR-15 Triggers

Most people are well-served by a quality mil-spec trigger like those from ALG (the QMS or ACT) or the BCM PNT.

Upgrading your trigger should be one of the last things a new shooter does to their rifle.

The bottom line is you should decide what use you need your trigger to fill, do your homework on the options, and buy quality. However, do not use the trigger as a crutch for bad fundamentals.

Discussion

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