From rifle build kit and stripped lower to functioning AR-15

Discussion in 'AR Pattern Rifles' started by BigWaylon, May 17, 2019.

  1. BigWaylon

    BigWaylon Head philatelist Staff Member Benefactor Charter Life Member

    Joined:
    Dec 18, 2016
    Messages:
    17,166
    Likes Received:
    55,686
    Location:
    Charlotte
    This is not a step-by-step guide on how to build an AR-15. But there have been several people recently asking about building their own, and lots of suggestions on how to to do it. So this afternoon I had my 12yo son attempt to assemble one with my guidance. Spoiler alert: what he didn’t know, was that he was building his own first AR-15. I snapped a couple pics along the way. I’ll include a brief description of what goes on in each step as well as what tools are needed.

    Here’s a pile of what we started with. It’s a PSA 16” 5.56 NATO 1:7 Midlength Nitride 13.5” Lightweight M-Lok MOE EPT Rifle Kit w/ MBUS Sight Set. Also bought a blem PA Microdot and absolute cowitness mount, plus a M-Lok compatible handstop. The last piece was the M4 Clone lower from PSA.

    To save you from searching:
    PSA = Palmetto State Armory
    MOE = Magpul Original Equipment
    EPT = Enhanced Polished Trigger
    MBUS = Magpul Back-Up Sight
    PA = Primary Arms

    496B3394-D985-4A05-93BF-A42385D0F3DD.jpeg

    The only things I did prior to today:
    1. Swapped the muzzle device to a YHM QD flash hider
    2. Tapped the takedown spring hole for a 4-40 screw
    3. Taped up the lower a little to protect it during roll pin installation and to cover up some custom engraving I didn’t want him to see until it was done

    Now, I’ve done this a dozen or so times. I’ve yet to build an upper, but I’ve never bought an assembled lower or a complete AR (the 15-22 doesn’t count). The first AR I ever held was an SBR that I built the lower and bought the upper.

    I’ve found Brownell’s site to be very helpful when assembling a lower. You can start here:
    https://www.brownells.com/aspx/learn/learndetail.aspx?lid=11011
    There are separate sections for each little step. There’s a short video you can watch, and also a PDF you can print out. I still use the printed copies each time. I’ll admit this discussion will have a slight “editing flaw”. I saw Trigger on the top of the page and went straight to the Trigger Guard step. It was supposed to be Trigger Group. So I’ll walk through it in the order they do, and the issue will just be that the pics will be a little off (you’ll see the trigger guard in the pic of the trigger group, when it shouldn’t be installed at that point).

    Once you have all the PDFs printed out, read through them.

    The next thing I’ve found very helpful is a picture of all the small pieces of a LBK (Lower Build Kit). I set it on the table, open all the little baggies, and match the parts up to make sure I’m not missing anything before I start. Most kits are the same, but some will includes extras. For example, the two PSA kits I’ve done this month both has one extra spring and one extra detent. When everything is in place, it’ll look like this:

    C0F5FE45-3BDB-47D3-99F2-4AFF6955E213.jpeg
     
    Last edited: May 17, 2019
    USMC6094, NKD, BBD280 and 7 others like this.
  2. BigWaylon

    BigWaylon Head philatelist Staff Member Benefactor Charter Life Member

    Joined:
    Dec 18, 2016
    Messages:
    17,166
    Likes Received:
    55,686
    Location:
    Charlotte
    1. Installing the magazine catch
    Tools required: none, although something slim enough to fit into the mag catch button hole will be helpful
    Parts used: magazine catch, magazine catch spring, magazine catch button
    Actions taken: This one is real simple. You’ll set the catch in from the left side, then the spring and button from the right side. You have to spin the catch around to the point the threads become flush with the button. You can push the button in with a finger, but something like a punch, bullet, clevis pin (which you’ll have around to make a later step less like to leaving you cussing like a sailor) is probably easier.

    When you’re done, it’ll look like this:

    4AB4790D-959B-4F69-8936-3A42B629319C.jpeg EA2058B3-2BD0-4199-BDC8-382356EB1D44.jpeg

    At this point you can function test the mag release.

    2. Installing a bolt catch
    Tools required: a punch and a small hammer; it can also be done with channel locks if you’re brave, and there’s actually specified tools made for it; you’ll also want to tape up the raised area on the lower or you’ll scratch it up pretty good
    Parts used: bolt catch, bolt catch spring, bolt catch buffer, and bolt catch roll pin
    Actions taken: spring goes in a hole, buffer sits in the spring, you hold the bolt catch in place and hammer the roll pin into place (from left to right in the pic below); you might want to start the pin before the spring/buffer/catch are in place to make it easier

    F4BD1D4B-08AE-4D80-9858-157974CBD49E.jpeg

    3. Installing the pivot pin
    Tools required: none, but a 1/4” clevis pin and a punch or Allen wrench will turn this into a 30 second process instead of a 10 minute swear-fest chasing a detent and spring around the room; another tip is you can put the lower into a gallon ziploc for this step to catch any pieces that launch
    Parts used: pivot pin, pivot pin detent, pivot detent spring
    Actions taken: you drop a spring into a hole, followed by a detent, and then slide the pivot pin in place; the easy way to do it is slide the clevis pin in from the left so the hole at the end lines up with the hole in the lower where the spring goes...then drop the spring into place and the detent; use the punch or allen wrench to push the detent down compress the spring until the allen/punch barely comes out the other side of the clevis pin hole

    81B12495-D743-4721-A977-3AB24408196A.jpeg

    at this point, rotate the clevis pin (easy to do in one motion with the allen/punch) about 90° so the spring and detent are trapped in place; then the dangerous part...holding a finger over the far end of the clevis pin, push the pivot pin in from the right to push out the clevis pin; make sure the pivot pin is rotated to that the detent engages the groove in the pin

    EE5B3505-5DF7-4F6B-9535-6040104CE356.jpeg
     
    Last edited: May 17, 2019
    Jeppo and JRHorne like this.
  3. BigWaylon

    BigWaylon Head philatelist Staff Member Benefactor Charter Life Member

    Joined:
    Dec 18, 2016
    Messages:
    17,166
    Likes Received:
    55,686
    Location:
    Charlotte
    4. Installing the trigger group
    Tools needed: none; having a punch handy could help, but not required
    Parts used: trigger, trigger spring, trigger pin, hammer, hammer spring, hammer pin, disconnector, disconnector spring
    Actions taken: install trigger spring on trigger, set disconnector spring into top of trigger and place disconnector on top, then set that assembly into the FCG (fire control group) pocket of the lower; push the trigger pin in, usually from left to right, making sure the disconnector hole is lined up with the trigger hole...you can use the punch from the right side to help get it all lined up; install hammer spring on hammer, place it into the FCG pocket, and insert the hammer pin...again left to right and use the punch from the right side if you have issues getting it lined up

    Warning: this is probably the easiest thing to screw up, whether it’s your first time or tenth time...mainly by not putting the springs on the right way; look closely at pics to make sure they properly aligned, like this:

    1E9D1E54-C6B6-4388-B258-66803667349D.jpeg

    Should look something like this when done (but you won’t have the trigger guard in place if you follow Brownell’s order):

    072CCF4B-08EE-49F3-A49D-39435F52D647.jpeg

    6CCF848F-B61D-4B15-B0A2-CF3069679BBC.jpeg

    5. Installing the safety selector and pistol grip
    Tools required: will depend on what type of screw comes with your pistol grip; normally a long flat blade will work...but the screw in the last two I did also had the ability to use an allen wrench
    Parts used: pistol grip, pistol grip screw, maybe a pistol grip lock washer, selector, selector spring, selector detent
    Actions taken: hammer needs to be push down (it should lock in place, insert selector into the left side with it oriented in the Safe position; flip receiver over and drop selector detent into hole (unlike the pivot/takedown detents which are the same on both ends, the selector detent needs to be dropped in with the point towards the selector; insert spring into hole in pistol grip and slide grip over tang on lower, being careful to line spring up with hole you dropped detent into; tighten grip screw with whatever the required tool is for your situation

    1BA7E88D-23FD-4576-A665-22C5BB840F4C.jpeg

    6. Install trigger guard
    Tools needed: this will vary depending on your lower and trigger guard; for mine, I needed a small allen wrench and a pair of channel locks; I’ve done the last two this way...previous I used a small hammer and punch instead of the channel locks; there’s also a specific clamp made to do this; if you use a hammer, you must support the other side of the lower (I always used a roll of tape to test it in) so you don’t snap an ear off the lower
    Actions taken: set the trigger guard in place, install the screw in the front of the trigger guard, and the roll pin in the rear; note that some actually have spring loaded detents so you just pop it in place

    This is one of the simplest, most straightforward steps...but it also the step that is most like to damage your lower beyond repair (as opposed to just a big scratch during the bolt catch step); you do not want to break one of the ears off!

    (Remember, you’d have the FCG already in place, and see the trigger in this pic, if you did it in the correct order)

    4641FB10-848C-46CB-827F-95648175A41C.jpeg

    8. Assembling the stick (there are two separate sections on the site depending on fixed vs telescoping, and with the wide variety of stocks/braces out there this is just a general discussion
    Tools needed: castle nut wrench; a 4-40 tap and 1/8” set screw aren’t required, but make this step much easier (your lower may actually already be threaded for the screw...all my Aero’s are and so was one of my Spike’s)
    Parts used: buffer tube (AKA receiver extension tube), buffer spring, buffer, stock, buffer retainer, buffer retainer spring, takedown pin, takedown pin detent, takedown detent spring, end plate, castle nut
    Actions taken: if you’re going to use a 4-40 set screw, thread the hole, insert takedown pin from right to left, drop detent into hole in rear of receiver, insert takedown detent spring, install screw to hold it in place (hopefully without launch the spring across the room, or into your eye); if you’re not going to use the set screw, you need to have the castle nut on the buffer tube with the wrench cutouts facing away from the receiver, and the end plate slid on so that the tab sits in the groove on the tube (this will make a lot more sense when it’s in your hand); screw the tube into the receiver until it comes close to the buffer retainer pin hole of the receiver; at this time you’ll put the buffer retainer spring into the receiver and then the buffer retainer on top of that, then screw the tube in just enough to catch the buffer retainer; you’ll need to rotate the tube just enough to be able to drop the takedown detent and spring into the hole, rotate it back and push the end plate into the indention on the back of the receiver; tighten the castle nut to hold the end plate in place; install stock/brace into buffer tube, insert buffer spring and buffer into extension tube

    E7C4F464-6A5A-46CC-8A1E-3503D1EDCE43.jpeg

    434DA872-AD15-45EA-9D8B-84C9350000BE.jpeg

    03069D29-3EA5-4967-8D72-40C538A3F753.jpeg
     
    Last edited: May 17, 2019
  4. BigWaylon

    BigWaylon Head philatelist Staff Member Benefactor Charter Life Member

    Joined:
    Dec 18, 2016
    Messages:
    17,166
    Likes Received:
    55,686
    Location:
    Charlotte
    At this point, you’re ready to slide the takedown and pivot pins out and attach the upper.

    I hope that allays some of the fears/hesitations you might have to tackle it yourself. It’s really just a series of small steps. The first time will take you a little longer, but it’s something that won’t really take more than 30 minutes in the future.

    Now...for this specific build, here’s where we are:

    DA1FBD32-7B4C-431D-8FF0-E14A0522CD70.jpeg

    I had him remove that piece of tape to see the M4 markings. His first question was “why does it say Property of US Government”?

    274F9AE6-514B-47E6-9C23-862D0AB1C11E.jpeg

    Then I had him flip it over and remove the last small piece of tape...

    43D0E56D-9137-45CD-BA41-DBACE792FC4E.jpeg

    I did capture his reaction on video, but not posting that here. He was pretty excited.

    I handed him a box to open...400 rounds of .223 and three 20rd PMags.

    1EF0A21E-B881-445C-8E09-8A6B9AABE312.jpeg

    B1F01F81-AC80-4907-BE09-FE680F6C455F.jpeg

    Put the PA red dot on after swapping to the cowitness mount. Added the MBUS set and my Omega. (Didn’t remember about the handstop, which was sitting on the table the whole time we were working, until after I’d out everything back up)

    0ACFFFCD-8B43-4218-A01D-15A1DE252234.jpeg

    We’ll get it out to the range to get it sighted in sometime fairly soon.
     
    Last edited: May 17, 2019
  5. kcult

    kcult Change my mind. Charter Member Supporting Member

    Joined:
    Dec 17, 2016
    Messages:
    5,338
    Likes Received:
    10,805
    Location:
    ChesCo SC
    Dang it!
     
    BigWaylon likes this.
  6. jmccracken1214

    jmccracken1214 Well-Known Member Supporting Member

    Joined:
    Jan 12, 2017
    Messages:
    3,635
    Likes Received:
    2,857
    Location:
    Thomasville, North Carolina
    Youre a brave man @BigWaylon

    I use WAY more tape than that for the bolt catch lol. Ive got longer punches now which make it a lot easier.
     
    BigWaylon likes this.
  7. BigWaylon

    BigWaylon Head philatelist Staff Member Benefactor Charter Life Member

    Joined:
    Dec 18, 2016
    Messages:
    17,166
    Likes Received:
    55,686
    Location:
    Charlotte
    Alright...I think that’s it. At least it’s all the pics I took. :D
     
    ronn47 likes this.
  8. Jerzsubbie

    Jerzsubbie Senior Member Charter Member Benefactor Supporting Member

    Joined:
    Dec 16, 2016
    Messages:
    2,462
    Likes Received:
    2,832
    Location:
    Huntersville
    That’s a pretty awesome gift!! Hopefully you had him assemble some it so he could also say that he built his own AR.

    Interesting that you mentioned putting the bolt catch roll pin in from L to R and as I’ve always done it the opposite. Don’t know why specifically, just have. Any reason to go L to R?

    Also since you posted a pic of them, (not your pic, I know) those yellow JP trigger springs are nice. Pair them with the PSA EPT trigger and it’s actually pretty darn nice! Those springs are like $12.

    And building uppers is pretty easy IF you have a bench vise. I’ve done it without but it’s a pain! Now, I prefer to build the entire rifle piece by piece.
     
  9. BigWaylon

    BigWaylon Head philatelist Staff Member Benefactor Charter Life Member

    Joined:
    Dec 18, 2016
    Messages:
    17,166
    Likes Received:
    55,686
    Location:
    Charlotte
    ...and by all means, if something needs to be corrected or clarified, let me know. I didn’t write it up as I went, it’s was all done after the fact. Let me know what would help, where you’re the one asking the question or you see something that needs to be changed.
     
  10. BigWaylon

    BigWaylon Head philatelist Staff Member Benefactor Charter Life Member

    Joined:
    Dec 18, 2016
    Messages:
    17,166
    Likes Received:
    55,686
    Location:
    Charlotte
    Yep, he did some of it. I did the FCG pins and knocked in the roll pins, but the rest was him.

    For no other reason than Brownell’s site said:
    4. Use the number 3 roll pin holder to start the bolt catch roll pin from the front of the receiver.

    R to L sure would reduce the chance of marring the receiver, but I just keep on doing it the other way. :confused:
     
    Jerzsubbie likes this.
  11. mike59

    mike59 Happy, happy, happy Life Member

    Joined:
    Feb 16, 2017
    Messages:
    203
    Likes Received:
    245
    Location:
    Raleigh
    Very cool on 2 fronts ...
    1) doing it with and for your kid ... memories!
    2) for all of us interested in going down this road - thanks for taking the time to document it!
     
    BigWaylon likes this.
  12. Jeppo

    Jeppo Very LARGE Member Supporting Member

    Joined:
    May 26, 2017
    Messages:
    9,115
    Likes Received:
    13,843
    Location:
    Davidson County, NC
    Well done Pop. ;)
     
    BigWaylon likes this.
  13. dbracin

    dbracin Active Member

    Joined:
    Dec 19, 2016
    Messages:
    351
    Likes Received:
    341
    Location:
    North Carolina
    Very nice job, “DAD”
    Something he’ll remember a long time.
     
    Last edited: May 18, 2019 at 6:53 AM
    BigWaylon and Jeppo like this.