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Brownells – Installing a Drop-In Trigger In An AR-15

Navigate the technical aspects of personalizing your AR-15 with clarity and confidence with our concise guide from Brownells, Inc. This piece explores the practical process of how to seamlessly install a drop-in trigger into an AR-15 lower. From stripping the trigger, hammer, and selector to testing the final assembly, your comprehension of this key function in firearm customization will become crystal clear.

Accentuated by detailed instructions and professional advice, your journey will traverse through the secure installation of a Cormac single-stage trigger system. The complexities of setting the lower receiver in the vise block, inserting cross pins, and aligning the hammer yield to a simplicity that is well within an enthusiast’s grasp. Undoubtedly, the effectiveness of a well-installed McCormick’s trigger is a profound testament to true craftsmanship.

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Table of Contents

Understanding the Elements of an AR-15 Trigger

Before we delve into the process of changing the trigger of your AR-15, it’s essential to understand the function of this crucial component and its constituent parts.

Understanding the Function of an AR-15 Trigger

The trigger of your AR-15 is a core element of its firing mechanism. It serves as the control point for discharging the weapon. When you pull the trigger, it releases the hammer that subsequently strikes the firing pin and ignites the primer of the cartridge, causing the bullet to be propelled from the gun.

Identifying the Components of an AR-15 Trigger

The AR-15 trigger assembly is predominantly composed of the trigger itself, the disconnector, the trigger spring, the hammer, the hammer spring, and the safety selector. The trigger and hammer are pivotally mounted on pins, while the springs provide the necessary tension to reset the components after each shot. The disconnector ensures that only one round is fired with each trigger pull, and the safety selector enables the shooter to control the firearm’s discharge.

Preparing the Lower Receiver

Before we can install a new trigger system, the lower receiver of your AR-15 must be adequately prepared.

Removing the Existing Trigger, Hammer, and Selector from your AR-15.

Begin by ensuring your firearm is unloaded and the safety is engaged. Once this is confirmed, you can start removing the existing trigger assembly. This process involves pushing out the pins that hold the trigger, hammer, and selector in place and then carefully extracting each part.

Securing the Stripped Lower Receiver in a Vise Block

Secure the now-stripped lower receiver in a vise block. A steady receiver will provide a conducive environment for a seamless installation process. This step might not be necessary when operating in the field, but it is recommended when working on the gun in a more controlled setting.

Introduction to the Drop-In Cormac Single-Stage Trigger

We will now introduce the drop-in Cormac Single-Stage Trigger and highlight its features and how it operates in an AR-15.

Understanding the Features and Benefits of the Cormac Single-Stage Trigger

The Cormac Single-Stage Trigger is designed for uncomplicated installation. Its advantages include offering a crisp break, minimal overtravel, and fast reset, which makes for an enhanced shooting experience.

Becoming Familiar with Cormac’s Application on an AR-15

Concrete benefits extend to its application within an AR-15. Cormac’s all-in-one design replaces the standard trigger assembly parts, promoting ease of installation and improved performance.

Brownells - Installing a Drop-In Trigger In An AR-15

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Inserting the Cormac Single-Stage Trigger into the Lower Receiver

Let’s now move on to the process of installing the Cormac Single-Stage Trigger into your AR-15 lower Receiver.

Placing the Trigger into the Receiver

The initial step in inserting the Cormac Single-Stage Trigger involves merely dropping it into the receiver. There’s no need for additional components or disassembly, which simplifies the process.

Aligning the Cross Pins for Correct Installation

Once the trigger is seated in the receiver, the next step is aligning the trigger with the cross pins.

Managing Hammer Tension During Installation

It’s essential to manage the hammer tension adequately during installation. Having the hammer cocked prevents the hammer spring from interfering with the process and simplifies the insertion of the cross pins.

Securing the Trigger with Cross Pins

The trigger system must be secured in the receiver using Cross Pins.

Understanding the Role of Cross Pins in Trigger Installation

Cross Pins play a crucial role in securing the trigger inside the receiver and preventing lateral movement during use.

Ensuring Correct Placement and Alignment of Cross Pins for Secure Installation

Correct placement and alignment of the Cross Pins are vital to ensuring a secure installation of the trigger system. The pins should be inserted by hand and might require minor adjustments for accurate alignment.

Stabilizing the Trigger System with Halfmoon Clips

Stabilizing the trigger system with Halfmoon Clips further ensures secure installation and operation.

Explaining the Importance of Halfmoon Clips to Secure the System

Halfmoon Clips, also known as keepers, are used to secure the trigger and hammer pins in place. These tiny devices prevent the pins from moving or falling out, thus enhancing the firearm’s reliability and safety.

Installing Halfmoon Clips on the Hammer and Trigger Pins

Installation of the Halfmoon Clips involves attaching them to the hammer and trigger pins.

Performing Post-Installation Checks

Once the installation is complete, several checks are necessary to confirm correct functionality.

Testing the Installed Trigger for Correct Functionality

Testing the trigger’s functionality involves checking if it releases the hammer properly.

Making Necessary Adjustments if Needed

In case of any anomalies, it’s crucial to make immediate adjustments. This would involve realignment of pins or resetting spring tensions, mainly depending on the issue identified.

Installing and Testing the Selector

The next step involved is the installation of the selector.

Demonstrating the Insertion of the Selector into the Lower Receiver

Installing the selector into the lower receiver involves pushing the detent into the hole using a non-marring punch and sliding the selector in.

Testing the Selector for Correct Movement and Overtravel

Test the selector switch for correct movement by checking if it securely clicks into each mode — safe, semi-automatic, and automatic (where applicable). Check for excessive overtravel to ensure safe operation.

Performing Safety Checks after Installation

After completing installation, carrying out safety checks is of paramount importance.

Testing the Safety Functionality of the Installed Trigger

Check the safety mechanism by engaging the safety selector and attempting to pull the trigger. If installed correctly, the trigger should not move when the safety is on.

Ensuring that Selector is Functioning Properly During Safety Checks

Ensure that the selector is functioning correctly and fully engaging the safety mechanisms when the safe position is selected.


Summarizing the Process of Installing a Cormac Single-Stage Trigger

In conclusion, the process of installing a Cormac Single-Stage Trigger involves understanding the AR-15’s trigger mechanisms, preparing the lower receiver, getting familiar with the new trigger, correctly placing the trigger and securing it with Cross Pins and Halfmoon Clips, testing the trigger, the selector, and performing post-installation safety checks.

Reminding about the Ease of Installation and Benefits of the Cormac Drop-In Trigger System

Though these steps might sound complex, they can be swiftly completed with a little precision and patience. Besides, the effort is highly rewarded by the tangible benefits of the Cormac Single-Stage Trigger system — the enhanced shooting experience, the smoother function, and the faster trigger reset. You will not only up the performance of your AR-15 but also enjoy the satisfaction of personalizing your firearm.

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