Building a complete lower receiver from a stripped receiver, step by step:
By: FALARAK of AR15.com forums This document demonstrates just how easy it is to assemble a lower receiver. This whole process, start to finish, takes 30 minutes to an hour.... depending on your skill level. If you can poke small objects into small holes, then you can build your own receiver. There is a good reference for this whole procedure posted here: www.ar15.com/content/guides/assembly/lower/ however the guide below is a simplified version with real pictures to show you how easy this is to do.... if you are on the fence. Ok, lets cover the necessary tools. What you need: Honestly... there are NO special tools necessary. Some will argue its good to have roll pin holder tools, roll pin punches, etc..etc... the only tools I feel are really necessary are a small brass punch.... and light hammer. Everything else can be improvised. Thats it for tools! Now here are the step-by-step instructions: There is not really a special order you have to go in... common sense will tell you some things have to be put in first, before others... but for the most part its not really important. The order shown here is just the way I happened to go... I started with a stripped lower receiver:
Here is the parts list that comes with a lower parts kit....
Insert the mag catch on the left side of the receiver (side with all the words on it) and then install the mag catch spring from the right side.
Then, grab the mag catch button and push it towards the mag catch. Then, spin the mag catch to tighten it. Stop when the mag catch threaded post is flush or nearly flush with the button:
2. On to the bolt release. Get some masking tape and cover the lower receiver here: This is to keep accidental scratching from occurring as we tap in the bolt release roll pin in place.
Insert the roll pin, and tap lightly to get it started... but do NOT tap it all the way in yet. Insert the bolt release spring and plunger, with the spring in first and the plunger facing out:
Then, install the bolt release, holding spring tension on the plunger, while aligning the hole in the bolt release with the roll pin hole in the lower.... and using a punch, tap the roll pin all the way in. If you want to avoid marring the finish, place more tape over the roll pin area as it gets close to flush to drive it all the way home. 3. On to the front pivot pin. Some people have trouble with this one, with the detent being launched across the room. Just be careful, and its really no big deal. Insert the spring into the detent hole:
Then insert the detent. It will barely even start in the hole before you really have to push for all the spring pressure. Then, using the pivot pin, push the detent back while you insert the pivot pin into its hole in the receiver.
4. Trigger guard. This is pretty straightforward... push the spring loaded end in, and insert in the single hole in the receiver. Then align the rear end and tap home the trigger guard roll pin:
5. Drop the trigger and trigger spring assembly into the receiver.
Then push the disconnector on the top of the trigger, with the notch in the disconnector over the coil spring in the top of the trigger. Then using a trigger pin, insert it through the lower receiver... into the trigger, through the disconnector, and back into the other end of the receiver. This takes a lot of wiggling to get it though... but you can do it!
6. Next, grab the hammer/hammer spring assembly, and insert it in the lower. The two long legs of the hammer spring should rest on the top of the trigger ping installed in step 5. There is quite a bit of hammer spring tension... but squeeze the hammer into the receiver so that the hammer pin hole lines up with the holes in the lower receiver, and install the hammer pin. You might have to tap lightly to get the pin through the hammer, but just LIGHTLY. Cock the hammer.
7. Next, install the safety selector into the left side of the reciever. Install the selector detent, and spring into the detent hole:
Install the pistol grip and grip screw, taking care to ensure the selector spring goes into the hole in the grip.
8. Rear takedown pin: Install the detent and then the spring... and the takedown pin into the rear of the receiver. The stock will hold tension on this spring/detent, when it is installed, next:
9. Thread the rifle/carbine buffer tube slowly into the receiver... taking care with the takedown pin spring. The tube should be threaded in just up to the buffer hole.... and then insert the buffer stop pin and spring:
Then thread the tube a little more, so that it holds the pin in place, but does not touch the center part of the pin and bind its movement:
Then tighten the stock in place... this is a carbine stock. You can use the CAR wrench for the castle nut (shown) or the CAR nut.... and some people like to add a little blue loctite to this nut so it wont back off in the field:
Now, just insert the carbine/rifle buffer and spring. Cock the hammer back to make this easy. The spring goes in first, with the buffer in next... and push the buffer in past the buffer pin sticking up.
You are all done! Perform a trigger mechanism safety check, install your upper, and go shooting! Safety function check is described HERE and HERE