Once again we’re continuing our series on assembling your own AR-15 lower receiver. The next step in the process is the installation of the selector, detent and spring, and pistol grip.
To begin the installation, first cock the hammer. Do not let the hammer fall and strike the lower, as it may cause damage.
Insert the selector through the hole in the left side of the receiver.
Flip the receiver over and insert the selector detent with the pointed side toward the selector. Insert the detent spring into the pistol grip. Install the pistol grip onto the receiver. Ensure that the detent spring does not bind as it is placed into the detent hole.
Install the grip screw with washer.
Check the selector for proper operation. Move the selector to safe and pull the trigger. The hammer should not fall. Move the selector to fire and, with your finger over the hammer, pull the trigger. Make sure to catch the hammer as it is sprung forward to prevent it from striking the lower. Keep holding the trigger back and then cock the hammer. It should be engaged by the disconnecter when the trigger is released. Flip the selector back to “safe” and repeat this process.