Building a complete lower receiver from a stripped receiver, step by step: (or..... "assemble your own lower for dummies") This web page will demonstrate just how easy it is to build a lower receiver from a stripped 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. SUPER video of the entire process by DVDTracker here: www.lifelibertyetc.com/RangeBag/Video/LLE_AR15StrippedLower.wmv 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. That’s 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....
Click HERE for a bigger and detailed parts kit photo. Here are some helpful pictures on the trigger and lower parts kits, common areas of confusion:
1. 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 catch. Get some masking tape and cover the lower receiver here: This is to keep accidental scratching from occurring as we tap in the bolt catch 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 catch spring and buffer, with the spring in first and the buffer facing out:
Then, install the bolt catch, 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 lauched 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 it's hole in the receiver. Snap... bamn.... it just falls into place. :-)
4. Trigger guard. This is pretty straightforward... insert in the trigger guard with single hole side in the receiver. Then align the roll pin hole up with the hole in the "ears" of the receiver. BE VERY CAREFUL HERE. You must support the "ears" on the bottom side if you tap the roll pin in place. If you dont support the bottom ear, you could break it off when tapping the pin in place. Also, some roll pins or trigger guards are out of spec. If it takes what you think is too much force, or starts to deform your roll pin, STOP. Also - see below for an alternative method of installing this pin by squeezing the pin in place.
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: NOTE - you may not wish to use Loctite. It is not required. Especially if you think you might be taking it apart again soon. Loctite just helps assue it wont get loose on you while shooting, and some people never have a problem with this. Just use a DROP or two and it will break loose pretty easily though. The CAR wrench for the newer castle nuts is a good tool to have: www.bushmaster.com/catalog_parts_gunsmithing_p2.asp#223TELEWRENCH2
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
DO NOT DRY FIRE A LOWER. Dry firing of the assembled weapon is fine. However, if you allow the hammer to drop on a lower that does not have an upper installed, it will potentially damage the lower receiver. The hammer will strike the bolt catch, which will damage the bolt catch receiver area and pin. If you do it a couple times it will be fine... but continued dropping of the hammer will likely result in damagin the bolt catch, receiver, or both. As an alternative to driving pins in with punches, you can press them in:
Originally Posted By A_Free_Man: Here are pictures, how to press in the roll pins in the lower (works also for the roll pin for the FWD asst on the upper, too): Hold the roll pin in position with needle nost pliers, a little oil or grease in the hole helps:
Use large Vise Grip pliers, jaws taped to protect the receiver from scratches. Adjusting the pliers so that they just barely press the pin in with the handles all the way together gives maximum mechanical advantage:
Get the pin started in, and put in the spring, detent, and position the bolt catch:
Continue pressing in the pin by opening the pliers, turning the knob 1/2 turn at a time, and pressing the pin in little by little:
Now the pin is almost all the way in, it can be tapped in flush with a few light taps on a punch or an ordinary carpenters nail set:
Now let's do the trigger guard: Hook the trigger guard in the front, by the mag well, and swing into position. If you don't have the trigger guard in position when you try to start the pin, it will break off the tab of your expensive lower:
Press in as in previous post, turning the knob of the Vise Grip 1/2 turn at a time:
Almost there:
Now that you have it this far, finish by tapping in flush using punch or nail set:
Common Q&A: Q1. do any of the lower receiver parts need to lubed? A1. CLP is all you *need* for any part on the AR15/M16 rifle.... and at a minum should wipe down the FCG, safety, and pins, with CLP. That being said, on initial assembly, I like to use a little moly-grease on the sear engagement surfaces on the trigger and hammer, and inside the trigger and hammer pin holes. I place a dab of grease on the new pins, and work them in and out to lube the inside of the new fire control group. I also add a dab of grease to the safety selector, and takedown/pivot pins. Q2. do you ever find the trigger and hammer pin move, or are they held in place fairly well? Ive seen some locking pins, are they necessary? A2. If the FCG is installed correctly.... there will be no movement of the pins. There is a "j" hook installed in the hammer that firmly holds the hammer pin in place..... so that cannot move. Then, when the hammer is installed, one of the legs of the spring rest in the groove on the trigger pin, so that one cannot move. I dont see the real use of "anti-walk" pins unless you are running some sort of custom trigger that does not have these designs in place. Or, if you do not want the pins to rotate in the receiver, you can install oversized pins like in the RRA triggers, or a KNS pin set which locks them from moving sideway or rotating.
Q3. Any grease necessary on the buffer spring? A3. NO!!! A light wipe with CLP is all you need. NO GREASE on the buffer tube! That SPROING noise is NORMAL, and is a good thing. When you hear the noise change, that lets you know you need a fresh mag. Q4. My bolt catch is sticky. My bolt wont lock back or it is VERY hard to release. Is this normal? A4. NO!!! This is a common issue with new parts. The hole in the bolt catch should be large enough to easily allow the bolt catch roll pin to pass through. If it does not, then the bolt catch hole is out of spec. You can contact the vendor and have it replaced, or you can ream it out larger with a tiny drill or grinding bit in a dremel, or very small round needle file. This is a cast hardened part, and does not drill easily.
