We are ready to start assembling our stripped lower. If you have not read the introduction, please do that here before proceeding. You do not necessarily have to go in this particular order, but I have found it to work the best for me.
- Insert the magazine release into the lower from the left side. From the right side of the lower, slip the magazine release spring over the shaft of the magazine. Depress the spring with the magazine release button and press the button flush with the outside of the receiver. This will push the magazine release out the left side of the lower. Spin the magazine release clockwise to screw it into the mag release button.
- Add the trigger spring to the trigger. The “feet” of the spring should point forward. Put the trigger disconnector spring into the trigger making sure the larger end is pressed all the way into the trigger. Take the trigger disconnector and align the notch with the disconnector spring. Insert this assembly into the lower & have a trigger pin ready. Align the holes of the trigger and disconnector with the holes on the lower and insert the trigger pin. Push the pin all the way through leaving it flush with the outsides of the lower.
- You must insert the safety selector at this point. If you do not, it will not fit in later. It will be free spinning for now.
- Put the hammer spring onto the hammer so that the feet point toward the back of the gun and press the hammer forward. The feet of the hammer spring rest on the shaft of the trigger. Use your index finger to push the hammer into alignment with the lower and push your second trigger pin through the hammer making the pin flush with the lower. This will also secure the safety selector and keep it from falling out.
- Place the safety selector on “fire”. Insert the selector detent into the hole in the receiver just above the grip cutout. Place the selector detent spring in the pistol grip & slide the grip onto the lower. Tighten the pistol grip screw and lock washer into the lower. Tighten until there is no play or wobble between the grip and the lower. Your safety selector should now click into place as you move it between safe & fire.
- If a trigger guard needs to be installed, there are two basic kinds. The first kind of trigger guard has a spring loaded pin that inserts into the front of the trigger guard. The other trigger guards use a tiny allen screw that is tightened to hold the front of the guard in place. For all trigger guards the rear is held in by a roll pin. Simply hammer it into place.
- The front detent spring requires incredible fingernails or the smallest flathead screwdriver you have. The detent spring is dropped into the tubular space on the top right of the lower. Carefully press the takedown detent pin down and slide the front takedown pin (sometimes called the pivot pin) into place. Some of my friends do this inside of a clear gallon Ziploc bag to keep from launching the spring and pin across the room.
You may want to print off a lower parts schematic to help distinguish between a few of these parts. Also, be sure to check out Part 3 of 3 for detailed instructions on completing your lower!