Since the late 1950’s, Eugene Stoner’s original M16 design has changed through the years, even though it was at the time radical in appearance and built of “space age” materials. But the trigger group had a problem a sloppy and inconsistent pull running through various models and versions.
After arms manufacturers delivered the AR-15 to the civilian market in a legal, semi-automatic form, the demand for an improved fire control system arose. Responding to the demand, there was soon an avalanche of upgraded triggers.
Quick Take: The Best Drop-in Triggers for the AR-15
Here are the best Drop-in Triggers for the AR-15:
- Patriot Ordnance Factory - AR-15 Drop-in Trigger
- Velocity Triggers - AR-15
- CMC AR-15 Tactical Trigger Group
What Is a Drop-in Trigger
The standard triggers on most factory rifles consist of separate and loose pieces. This makes their installation more difficult. They end up with varying spaces between them
The newer concept of a drop-in trigger is a significant departure from the mil-spec AR-style fire control group. It means that the hammer, trigger, and disconnector are joined in a single case. This allows for an exact relationship between sear and hammer since the hammer and trigger pins in the housing are kept in the same relative locations.
Advantages of a Drop-in Trigger
This way, the popular self-contained "drop-in" triggers have solved two issues with stock AR fire control groups (FCGs) and AR trigger upgrades respectively. They’re now easier to install as well as being more consistent. In fact, drop-in triggers don't require any gunsmithing or specialized skills for installation.
Although the popularity of the drop-in trigger has been linked to more recent times, it actually first appeared over 50 years ago. For instance, the famous Russian Dragunov SVD marksman rifle from the early 1960s had a drop-in trigger group. The same is true of the lesser-known Taiwanese T86 assault rifle (an AR-15 clone) from the late 1990s.
Disadvantages of a Drop-in Trigger
One disadvantage of drop-in, self-contained modules is the non-adjustable trigger pull weight. This is set at the factory and typically fixed with thread locker because the end user is not supposed to touch it.
However, customers generally do have an option of selecting between 3, 4, and 4.5 lbs at the time of purchasing. It’s just the fine-tuning afterward that is an issue.
Quick Comparison Chart of the Top Options
Timney AR-15 Drop-in Trigger Module
Patriot Ordnance Factory - AR-15 Drop-in Trigger
AR-15 Triggertech AR-15 TT-AR-15 Trigger
Velocity Triggers - AR-15
Currently, many modular fire control units are available, including both single- and two-stage systems. In these short reviews, we’ll present some of the more popular drop-in AR-15 triggers out there.
Reviews of the Best Drop-in Triggers for the AR-15
The first self-contained "drop-in" trigger comes from the eldest and most reputable gun part manufacturer Timney Triggers, established in 1946. Many of their models are painted gold, appropriately. Timney is the gold standard for aftermarket triggers, and their AR-15 Drop-In Trigger module is no exception.
The most striking thing about this trigger group is that all components come in a shiny yellow aluminum housing. That’s what catches the eye, but the best thing is that it requires no gunsmithing or crazy modifications. Just drop it in with your factory AR hammer and trigger pins or new KNS pins.
As expected from such a reputable manufacturer, this trigger provides smooth, crisp, creep-free pull. It feels more like classic bolt action than a battle rifle trigger. Timney provides a very clean break with a short reset. That means you can quickly shoot a lot of rounds without much motion of your trigger finger.
Though this drop-in has a set screw for adjusting trigger return/pull weight, the Timney is tuned by the factory and then locked down. This single-stage trigger comes with a preset pull weight choice of 3 lb., 4 lb. or 4.5 pounds and features standard solid, slightly curved trigger bow.
The components are machined from tool steel heat-treated to 56-60 Rockwell case hardness for long service life with superior impact resistance. Besides trigger and hammer pins, the drop-in cassette is also secured by the set screws in the floor of the lower receiver.
The innovative CMC triggers were created by competitive shooter Chip McCormick and belong to the more affordable drop-in line of AR-15 triggers on the market. The CMC Tactical Trigger has a light, crisp break with almost nonexistent overtravel. It has a short trigger reset of roughly 2mm. The preset pull measures 3½ lb. pull.
This excellent match-grade single-stage trigger has all internal components tweaked at the factory to minimize take-up and over-travel. It comes in a stainless steel sheet metal trigger housing.
The entire module is held in the receiver by two slightly-oversized center pins to prevent trigger wobble. CMC offers its Tactical trigger group with a traditional curved trigger shoe or a skeletonized flat shoe.
Another favorite drop-in trigger group comes from Patriot Ordnance Factory (POF), a US firearms manufacturer based in Phoenix, Arizona. They produce a line of impressive AR-15 triggers for competition, hunting, and tactical applications.
Since 2004, POF has provided AR enthusiasts with several varieties of the self-contained drop-in triggers as well as an Enhanced Finger Placement trigger. All components are machined from A2 tool steel. They are nitride heat-treated to 70 Rockwell case hardness for the best strength and corrosion resistance.
This simple hard-coat anodized aluminum cassette comes with rubber urethane bumpers on the bottom instead of Timney set screws. An anti-rotate stainless steel pin kit made by renowned KNS Precision is included in the package, too.
The improved POF EFP (Enhanced Finger Placement) trigger supports the tip of your finger at the same low resting site for a precise and consistent trigger pull every time.
The custom-designed single-stage, non-adjustable POF EFP features a semi-curved trigger shoe with a solid 4.5-pound pull weight.
Canadian company TriggerTech differs from traditional functionality by using a roller bearing system, as opposed to their competitors who utilize designs with pivots and polishing to try to attain the best break possible.
TriggerTech uses rolling friction in the form of Frictionless Release Technology (FRT). Their designs, based on the roller system, help contribute to the minimal wear and tear on engagement surfaces. This helps ensure durability and high-end performance.
TriggerTech produces a non-adjustable drop-in triggers with a 3.5 or 5.5-pound pull depending on the model. The adjustable version can be adjusted from 2.5 to 5 pounds. You can make those adjustments with the supplied Allen key. Every turn of the trigger adjustment screw has an audible click that measures approximately 2 ounces.
TT-AR-15 two-stage triggers give you a clean break and have a minimal trigger reset of roughly 1mm without the worry of accidental discharge.
The TriggerTech TT-AR-15 comes in a housing made of aluminum. The rest of the working components are constructed with hardened corrosion-resistant stainless steel.
This Canada-based company started as a crossbow trigger manufacturer. Today they offer a variety of AR-15 drop-in triggers available in curved or straight blade trigger variants.
Once again our journey to the best drop in triggers brings us to Phoenix, Arizona. This time we visit a newer company called Velocity Triggers. Velocity was founded in 2008 by Tom Vehr, a designer and engineer with over 30 years of experience in manufacturing and assembling triggers for well-known makers such as Timney Triggers and Knight Rifles. The experience he brought from his former company is most easily seen in the personal feel similar to the Timney. But Velocity installs a little easier and costs less.
Velocity says their trigger-pull quality rivals a nice bolt-action rifle. A decent cost is another selling point - it’s about half the price of a lot of other aftermarket AR-platform triggers.
Velocity Triggers offers a true drop-in replacement trigger for standard AR-15 style weapons. Installation takes less than five minutes and requires triggers pins that are sold separately.
All Velocity Triggers are single-stage. They have a short and positive reset that is suitable for precision shooting as well as for 3-gun style competition use.
Despite its low cost, Velocity Triggers do not sacrifice quality. Their components are cut from tool steel with a very precise Wire EDM process. This is more accurate than almost any CNC mill.
The parts are heat-treated for the necessary hardness. The trigger housings are machined from 6061 T6 billet aluminum and coated with a green anodizing. Seven models are currently offered with trigger pulls ranging at 3, 4, and 4.5 lbs. All are available with curved or straight trigger blades.
As a novelty, they’ve recently introduced two new models to work specifically with the often-problematic steel-cased ammunition and 22LR conversions. Both models are available with either a straight blade or a curved blade. They have a 4.0-pound pull weight.
An AR-platform rifle is an ideal "kit" gun for do-it-yourselfers. A drop-In trigger is a logical upgrade for any AR fanatic to help you build a system tailored to your needs and preferences.
A simple drop-in installation matched with quality and precision-built trigger components will give you uniformly good, clean, crisp trigger pulls. In turn, this will lead to a consistent, tight shot group.
Aftermarket drop-in triggers can be pricey, but there are many affordable and quality self-contained triggers from a number of different manufacturers. Don’t feel trapped with the standard, gritty stock trigger of AR-15!