Step L3: Bolt Catch Installation
Objective: In Step L3 of lower receiver assembly, we will install the bolt catch assembly onto the lower receiver.
Tools Required
1: A mag well vice block is a good way to secure your lower during the installation of small parts.
2: Only required if building on an Aero Precision Enhanced lower receiver. The Aero Precision Enhanced lower uses a threaded pin to secure the bolt catch to the receiver instead of a roll pin.
3: Required if not building on an Aero Precision Enhanced lower receiver. Other receivers use a standard roll pin to secure the bolt catch to the receiver.
Components Required
| Quantity | Component |
|---|---|
| 1 | Lower Receiver |
| 1 | Bolt Catch |
| 1 | Bolt Catch Buffer |
| 1 | Bolt Catch Spring |
Instructions
CHECK THE MAG CATCH
Be sure that your magazine catch assembly is properly installed (per Step L2) and that you have verified the magazine engagement and release before you install the bolt catch. If you have not done this verification first, you may need to remove the bolt catch if further adjustment of the magazine catch is required.
Secure the Lower
If using a mag well vice block, install a mag well vice block into your vice and install your lower receiver onto it.
Step L3.0: Remove Existing Bolt Catch (replacement/upgrade only)
If you are replacing your existing bolt catch (or need to remove the bolt catch for any other reason), first ensure the firearm is unloaded.
Aero Precision Enhanced Lower:
Loosen and remove the threaded bolt catch pin using a 1/16″ hex key. Once removed, the bolt catch, bolt catch buffer, and bolt catch spring will fall free.
Standard AR Lower:
Drive the bolt catch roll pin out of the lugs in the lower receiver using a 3/32″ roll pin finish punch (preferably an offset bolt catch roll pin punch). Once removed, the bolt catch, bolt catch buffer, and bolt catch spring will fall free.
Step L3.1: Remove the Threaded Bolt Catch Pin (as applicable)
If you are using a receiver with a threaded bolt catch pin, remove the pin from the lower receiver.
Step L3.2: Lubricate the Bolt Catch Buffer Cavity
Add one drop of wet lube into the bolt catch buffer cavity.
Step L3.3: Install the Bolt Catch Spring
Place the bolt catch spring into the cavity on the left side of the lower receiver.
Step L3.4: Install the Bolt Catch Buffer
Place the bolt catch buffer into the cavity on the left side of the lower receiver with the rounded end facing outward.
Step L3.5: Lubricate the Bolt Catch Buffer
Place a drop of wet lubricant on the bolt catch buffer using a needle dropper.
Step L3.6: Align the Bolt Catch
Depress the bolt catch buffer and bolt catch spring with the bolt catch. Align the hole in the bolt catch with the bolt catch lugs on the lower receiver.
Step L3.7: Install the Bolt Catch Pin
Aero Precision Enhanced Lower:
Do NOT use thread locker
Feed the threaded bolt catch pin from the rear of the lower receiver, through the rear bolt catch lug, bolt catch, and into the forward bolt catch lug of the lower receiver. Using a 1/16” hex key, tighten the bolt catch pin. Do not overtighten (you will strip the threads of the screw and/or receiver).
Standard AR Lower:
TOOTHPICK SLAVE PIN
It may help to use a toothpick as a slave pin until you are able to secure the bolt catch with a roll pin.
Tap the bolt catch roll pin into the rear bolt catch lug of the lower receiver using a 3/32″ roll pin starter punch (preferably an offset bolt catch roll pin starter punch).
Using a 1/8″ steel pin punch, drive the bolt catch roll pin through the bolt catch and into the forward bolt catch lug of the lower receiver until the roll pin is nearly flush with the rear lug.
Use a 3/32″ roll pin finish punch (preferably an offset bolt catch roll pin punch) to drive the pin flush with the bolt catch lug.
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