Before beginning, make sure you have all the necessary tools and parts. You will need:
- a lower receiver
- a lower parts kit (which includes the trigger, hammer, disconnector, springs, etc.)
- an upper receiver
- a stock or buffer tube assembly
- tools (screwdriver, Allen wrench set, etc.)
1) Start by attaching the magazine catch to the lower receiver. Install it from the right side of the receiver and use a small screwdriver to tighten the set screw. Make sure not to over-tighten it.
2) Next, move on to the bolt stop assembly. Install this from the left side of the receiver using a small screwdriver to tighten the set screw. Again, make sure not to over-tighten.
3) The trigger guard can now be installed. There are typically two ways to do this – with the guard in the “down” position or “up” position. For ease of installation, we recommend doing it with the guard in the “down” position. Once the guard is in place, tighten the set screws.
4) The trigger can now be installed into the lower receiver. Start by inserting the front of the trigger into the receiver, then push down on the back until it snaps into place.
5) The hammer can now be installed. It will fit into the receiver in only one orientation, so make sure it is facing the correct way before inserting it. Once it is in place, use a small screwdriver to tighten the set screw.
6) The disconnector can now be installed. Start by inserting the front of the disconnector into the receiver, then push down on the back until it snaps into place.
7) The selector switch can now be installed. There are usually two ways to do this – with the switch in the “safe” position or “fire” position. For ease of installation, we recommend doing it with the switch in the “safe” position. Once the switch is in place, use a small screwdriver to tighten the set screw.
8) The pistol grip can now be installed. Start by inserting the front of the grip into the receiver, then push down on the back until it snaps into place.
9) The buffer tube assembly can now be installed. First, insert the back end of the tube into the receiver. There is a small hole in the bottom of the receiver that the tube will fit into. Once it is in place, tighten the set screw. Then, screw on the end cap until it is tight.
10) The stock can now be installed. First, insert the back end of the stock into the buffer tube assembly. There is a small hole in the bottom of the tube that the stock will fit into. Once it is in place, tighten the set screw. Then, pull the stock until it is tight against the back of the receiver.
11) The last step is to install the sights or scope. If you are using iron sights, they will typically clamp onto the top of the receiver. If you are using a scope, there will be a mount that attaches to the receiver. Once the sight or scope is in place, tighten all screws.
Your lower receiver is now complete!