Lower Receiver Assembly (AR-9, AR-15, and AR-10/LR108)
Step L5b: Trigger Group (Drop-In) Installation
Objective: In Step L5b of lower receiver assembly, we will install the cassette style trigger group into the lower receiver.
Tools Required
1: If using anti-walk trigger/hammer pins. Hex keys are usually supplied with anti-walk pins.
2: May be needed for removal of existing hammer/trigger pins.
Components Required
| Quantity | Component |
|---|---|
| 1 | Lower Receiver |
| 1 | Cassette/Drop-In Trigger |
| 2 | Trigger/Hammer Pins |
Instructions:
Step L5.0: Remove Existing FCG and Safety (replacement/upgrade only)
If you are replacing your existing fire control group (or need to remove it for any other reason), first ensure the firearm is unloaded.
You may need to remove the safety selector, which will require that you also remove the pistol grip.
Anti-Walk or Anti-Rotation Pins
You will need to remove the pins per the manufacturer’s instructions. Typically, you will need to remove one or more screws using a hex key.
Once the cap screws are removed from the pins, follow the instructions for removal with standard pins, below.
Standard Pins
Begin by removing the hammer pin (forward-most pin). With the hammer in the set position (engaging the sear of the trigger) and while applying light downward pressure to the hammer, use a 1/8″ nylon or brass punch to push the pin out of the receiver. You may need to tap the punch with a gunsmithing hammer. Once the pin is clear of the hammer, the hammer and hammer spring can easily be removed from the receiver. Be sure to hold the hammer firmly, as the spring tension will want to fling the hammer out of the receiver.
Next, remove the trigger pin. The procedure is equivalent to that above for the hammer pin. While applying light downward pressure to the trigger, use a 1/8″ punch to push the trigger pin out of the receiver. The trigger, trigger spring, disconnector, and disconnector spring can now be removed from the receiver.
Step L5.1: Seat and Secure the Trigger
Carefully drop the trigger assembly into the trigger pocket of the lower receiver.
Step L5.2: Install Hammer Pin
Insert the hammer pin into the hammer pin hole (front) in the receiver and through the hammer bore of the trigger.
If you are using anti-walk or anti-rotation pins, install the cap screw on the hammer pin.
Step L5.3: Install the Safety Selector
In many cases with cassette style triggers, you will not be able to install the safety selector once the trigger pin is installed. As such, you should install the safety selector into the lower receiver before you install the trigger pin. Install per Step 6.
Step L5.4: Install Trigger Pin
With the safety selector installed, insert the trigger pin through the trigger pin hole (rear) of the receiver and through the trigger pin bore of the trigger.
If you are using anti-walk or anti-rotation pins, install the cap screw on the trigger pin.
Step L5.5: Tighten Tension Screws (if applicable)
If the trigger is equipped with tensioning screws, tighten the screws per manufacturer instructions.