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Thread: How to Assemble an AR15 Instructions

  1. #1
    Veteran KnobCreek's Avatar
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    How to Assemble an AR15 Instructions

    I know there are a lot of good instructions on how to assemble an AR15 already out there, but I thought it’d be nice if one of our own members provided some instructions as well…besides, I was bored and I had the time in between me looking for a job.
    I received three Double Star lowers today and decided to snap off a couple pictures as I was going about assembling them. What normally takes about 30 minutes, took me 2 hours today, mainly because I had to set things up to take the pictures, position my fingers and parts so that I could snap off some clear shots, and drinking a couple cans of beer kindda impaired my vision.
    OK, here goes…
    Tools

    There are a few tools that help facilitate in putting together these kits, but none of them are absolutely necessary. Minimum requirements include a hammer and punch to drive in a couple of roll pins, a flat-blade screwdriver for the stock screw, and either a screwdriver or Allen key for the pistol grip screw.
    • Roll Pin Punches - to drive roll pins (3/32", 1/8", 5/32"); these have a small raised projection in the face of the punch to automatically center the punch and prevent the roll pin from collapsing
    • Hammer - used to drive the roll pins
    • #10 Flat-Blade Screwdriver - used for A2 stock screw and some pistol grips
    • Block of wood - base to support receiver when driving roll pins
    • Allen Key - used for some pistol grips
    • Telescoping Stock Wrench - to tighten telescoping stock lock ring
    The Parts

    The lower receiver parts kit contains 30 parts not counting the stock assembly, the receiver, or the pistol grip. Most of these parts are covered in oil to prevent rust; wipe all the excess oil off before assembly. The following is a diagram of the parts that come in an LPK:



    SPRINGS
    • Bolt Catch Spring - easily confused with the disconnector spring; disconnector spring is tapered though.
    • Buffer Retainer Spring - second largest spring in the kit.
    • Disconnector Spring - similar to bolt-catch spring, but identifiable because one end is wide than the other.
    • Hammer Spring - larger of the two similar springs.
    • Magazine Catch Spring - this is the largest spring in the kit.
    • Pivot Detent Spring - same as the takedown detent spring, so there are two in a kit.
    • Selector Spring - similar to the takedown and pivot detent springs, but there will only be one of these.
    • Takedown Detent Spring - same as the pivot detent spring, so there are two in a kit.
    • Trigger Spring - the smaller of the two similar springs.
    PINS
    • Bolt Catch Buffer
    • Bolt Catch Roll Pin - smaller of the two roll pins.
    • Hammer Pin - same as trigger pin; can be inserted from either side.
    • Pivot Detent - same as takedown detent; both sides usually rounded.
    • Pivot Pin - larger of the two large pins.
    • Selector Detent - one end is flat, the other pointed.
    • Takedown Detent - same as pivot detent; both sides usually rounded.
    • Takedown Pin - smaller of the two large pins.
    • Trigger Guard Roll Pin - larger of the two roll pins.
    • Trigger Pin - same as hammer pin; can be inserted from either side.
    • Bolt Catch
    • Buffer Retainer
    • Disconnector
    • Hammer - will have a J-pin already installed.
    • Magazine Catch
    • Magazine Catch Button - some are plastic, some metal.
    • Pistol Grip Lock Washer
    • Pistol Grip Screw - some are Allen-head, some use a slotted pan-head screw
    • Selector
    • Trigger
    • Trigger Guard - some are metal, some plastic. Will already have a detent installed on its front end.
    Assembly

    Here are the steps that I normally follow when assembling an AR.
    First, open up a can of your favorite brewskie. I’m partial to Killian’s Red, but I only had Miller Genuine Draft, so I had to make due with what was on hand.
    You want to always work in a well-lit area, and it is helpful to work on a flat, hard and light colored surface. There are many small pins and springs, and they have a tendency to roll or fly away and disappear forever. Layout your parts and try and identify them. The springs look very similar, but have slight differences that make it important to not mix them up.
    Here are the tools that I shall be using:

    This is the parts kit, upper and lower, that I shall be assembling:

    And these are the lowers that just came in, one of which, will be used in this instruction:


    I normally begin with the magazine catch assembly:
    These are the parts you’ll be working with:





    Install magazine catch into recess on left of receiver then Install spring onto threaded portion of magazine catch from the right side of receiver. Screw button onto threaded portion of magazine catch 3 or 4 turns.



    You can use a punch (larger than hole in magazine button) or wooden dowel to push in the magazine button so you can turn the magazine catch clockwise until the end of the catch is flush with the magazine button head, but I just use a plastic safety chamber flag.




    Bolt Catch Assembly:
    Next, I do the bolt catch assembly. Here are the parts you’ll be working with:

    When installing the bolt catch, first drive the roll pin about halfway into the rear hump from the rear of the receiver. I used an old credit card to protect the receiver’s finish while using a punch and hammer.


    Install spring and bolt catch plunger (on top of spring and small end into the receiver) in hole on left side of receiver.

    Install bolt catch in receiver; it only fits on one way and then the pin can be driven the rest of the way




    Next is the trigger guard assembly
    Plain and simple:

    Make sure you properly support the bottom flange of the receiver by laying the receiver on a block of wood. If you don’t, that flange will definitely break right off. Drive roll pin into receiver and rear of trigger guard using drive pin punch.



    The next step is installing the front pivot pin
    These are the parts you’ll be using:

    Insert spring and detent into receiver:

    This is perhaps the hardest part of the lower assembly, so if available, use a pivot pin installation tool.


    I just used a punch to help keep the spring and detent pin down while I slapped on the pivot pin:

    And here is the pin installed:



    The next step I do is the trigger assembly.
    These are the parts you’ll be working with:


    This is how the parts should look once you installed the springs:



    Shoulder trigger spring onto trigger with ends of spring forward and under. Install disconnector spring with the wider portion of spring down towards trigger and push until it locks in there. Position disconnector on top of trigger, where trigger pin will hold both in place. Insert trigger assembly into receiver.

    I use another push pin to help with alignment while I insert the trigger retaining pin through receiver, trigger, and disconnector.


    Install trigger and use the same method to install hammer pin:



    Next assembly is the selector switch

    These are the parts you’ll be using:


    With the hammer cocked back, insert from left side of receiver, selector pointing up in the 'fire' position.




    The following is part of the selector switch assembly, but pertains to the pistol grip assembly as well..
    Insert detent detent, pointed end towards the selector, and the spring into the receiver from the bottom.

    Carefully compress the spring with the grip and make sure spring fits into hole in grip.


    Use the screw and lock washer to secure the pistol grip to the receiver:


    These parts should be the last in your pile:


    We shall be using them to install the collapsible buttstock and the rear retaining pin.
    Install detent/spring into receiver:

    Install buffer retainer and spring:

    These are the parts for the collapsible stock assembly:

    Install buffer tube, backplate, and locking ring onto receiver and depress retainer when necessary to get it to rest under the extension tube. Turn tube until it is about 1/4 turn past the correct location.


    Use a stock wrench to tighten everything up:

    You can stake the locking ring to the backplate if you so desire:

    And round the corner and heading home, this is the completed lower:


    Just mount a favorite upper, and go shoot:



    Last step is to open up another brewskie and smoke a cigarette.
    Do not be anxious about anything, but in everything, by prayer and petition, with thanksgiving present your requests to God. And the peace of God, which transcends all understanding, will guard your hearts and your minds in Christ Jesus.

    Philippians 4:6-7:

  2. #2
    RIP 1/6/2012 okie shooter's Avatar
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    Don' know if I will ever build one my self, but I have two and need to do some work on change out of some parts, Thanks for the nicely done instruction set. It is much less intimidateing when there are good pictures with them too.

    P.S. sounds like your last comment gets all the bases covered, by the alphabet guys, too.
    Still building bigger and better bombs for your brighter tommrows(aw heck and takeing them apart and demilling them for that tommrow too)

  3. #3
    Veteran KnobCreek's Avatar
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    Yeah, I was very intimidated my first time around. I find that it helps if someone shows you the first time around, but since we can't always do this, the next best thing is to show someone using pictures....
    Do not be anxious about anything, but in everything, by prayer and petition, with thanksgiving present your requests to God. And the peace of God, which transcends all understanding, will guard your hearts and your minds in Christ Jesus.

    Philippians 4:6-7:

  4. #4
    Veteran KnobCreek's Avatar
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    BTW, I've got 2 more receivers to do today and I lost track of how many more that are on back ordered via various vendors. That's OK, it should give me time to purchase more uppers.

    The next instruction I want to document is building an upper from stripped parts.
    Do not be anxious about anything, but in everything, by prayer and petition, with thanksgiving present your requests to God. And the peace of God, which transcends all understanding, will guard your hearts and your minds in Christ Jesus.

    Philippians 4:6-7:

  5. #5
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    Can I add a couple tools I thought were also helpful during an AR15 build, although they aren't required?

    One is the DPMS receiver claw found here: http://www.dpmsinc.com/store/products/?prod=1675. It allowed me to install a Larue FF tube without having to make that ugly action block mod you see on barfcom. It was pretty sturdy and held up through removing and torquing down a barrel nut.

    Another one is this brass hammer and punch set found here: http://www.midwayusa.com/eproductpag...eitemid=973259. The soft brass didn't mark up the finish on my AR like a steel punch would if I slipped.

  6. #6
    97th Signalman's Avatar
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    Thumbs up AR build instructions

    That is a great instrucional sequence. If the Webmaster has a setup for stickies or permenant technical resources it should go there.

    97th Signal Bn, 7th Army Main Communications, Germany, 1960-63

  7. #7
    Veteran kpd007's Avatar
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    Great work Knobcreek. This is a very good tutorial and just as good as others I have seen in other places. Thank you.
    "Sheep have two speeds: Grazing and Stampede"

    Lt. Col Dave Grossman

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    Veteran Alaskagrown's Avatar
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    you didn't use all of those tools...

    so when are you gonna show us how to assemble the upper?

  9. #9
    Senior Veteran Smokehouse69's Avatar
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    It's been a while since I assembled an AR, about 29 years. I guess I'm gonna have to buy myself one so I can get some practice!!

  10. #10
    Veteran KnobCreek's Avatar
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    Quote Originally Posted by Alaskagrown View Post
    you didn't use all of those tools...

    so when are you gonna show us how to assemble the upper?
    Well, I have a complete upper and a fluted barrel, I'm just waiting on receiving my delta ring assembly, gas tube, barrel nut and a couple other things. I was hoping to begin with a stripped upper, but can do that some other time.

    Yeah, I didn't use all the tools; I just wanted to take a picture of what I use for a complete build from stipped parts.
    Do not be anxious about anything, but in everything, by prayer and petition, with thanksgiving present your requests to God. And the peace of God, which transcends all understanding, will guard your hearts and your minds in Christ Jesus.

    Philippians 4:6-7:

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