How to Build Your Own AR-15

by Gilfner

I recently completed a project AR-15, M-4 style.  I am really pleased with how it came out. There are some advantages to building one yourself.  First is cost, but not necessarily the overall cost.  It’s the ability to “pay as you go”. 

What I mean by this is you can pay for the parts as you can afford them.  Then once you have all the parts, you put the gun together.  It can be as short or as long a project as you can afford. 

Another advantage is you get it done the way you want.  Want a gas piston system?  Certain brand of fore end rail?  Front site or just gas block?  A special stock?  Only US made parts?  A different caliber?  You decide!  The other advantage is the better understanding of how the rifle works you’ll gain from doing the work yourself.  In a WROL there may not be a gun smith to fix your gun for you.

 The only negatives I can come up with are that resell value will not be as good as with a commercially assembled rifle by a reputable manufacturer and there is at least one way that you could break the lower receiver during assembly that would ruin it.  So don’t sell the rifle and know what the pitfalls are during assembly, so you can avoid them!  Easy!

Figure 1 – Current configuration

If you are wondering how difficult it is, I would say not very.  If you can field strip an AR-15, you can probably put the gun together.  The tools you will need will vary depending on what you assemble yourself.  If you only assemble the lower receiver, you will need a stock wrench (Most gun shops sell AR-15 combo wrenches that will have a stock wrench), a roll pin punch & a hammer.

If you assemble the upper, you will need more tools and of course, there are a TON of specialized tools, each of which makes specific parts of the assembly a lot easier.  But they aren’t required either.

The first thing you have to do is find a local gun shop that carries stripped lower receivers.  I’ve seen them sell for anywhere from about $90 to $200.  The thing with the lower receiver is that it’s the serial number part of the gun that must be purchased from an FFL dealer.  Even if you order one from the net, you will still need a local FFL dealer to ship it to.

Everything else on the gun is just a replaceable part that doesn’t require an FFL dealer to purchase.  There are literally web sites (such as Model1 or Del-Ton and even Brownell’s that sell the rest of the parts for the gun, you simply supply the stripped lower receiver.

So, either you can go to one of the sites that sells the rest of the parts, pick your options from the drop down menus and buy all the parts at once.  Or you can pick parts from different places.  In addition to the stripped lower receiver, you will need an upper receiver assembly including a bolt carrier group and a lower parts kit.

Some of the lower parts kits come with everything, but if it doesn’t come with a stock & buffer tube assembly, you will need those as well.  If you get a flat top receiver and/or just a front gas block (I.E. no front site), you will need to plan on an optic or sights.  I chose to purchase an assembled upper receiver and barrel from Midway USA.  I was a firearms instructor in the Air Force and where I did barrel changes, so I didn’t feel a need to assemble the upper receiver myself.

I wasn’t trying to do it (I just bought what was on sale), but the upper I got had a thin profile barrel, which makes it lighter weight.  At the same time I purchased a DVD from Midway USA that gave detailed instructions for assembling rifle, including both the upper & lower receivers.

Of course, all through the video, they are using their specialized tools for making assembly easier, but you will see exactly what goes where & how.  Watching the video kept me excited & motivated to get the remaining parts

I picked up a DPMS lower parts (which didn’t include a stock & buffer) from my local shop and had them get me a Magpul MOE complete stock set with buffer assembly in foliage green.  Since it was a flattop receiver with a standard front site, I had them get me a MBUIS in matching foliage green and several foliage green Magpul magazines.

Once I had all the parts, it was time for assembly.  I did the assembly in about an hour (maybe it took longer, I was having too much fun) on my kitchen table.  I installed all the parts of the lower receiver including the buffer tube & stock.  I had to have my wife help me install the bolt catch/release roll pin.

Trying to hold the lower receiver, the bolt catch/release, the roll pin, the roll pin punch and use the hammer to tap it all in was just more than I could do with only two hands.  It was almost more than we could do with 4 hands.

Figure 2 – Bolt catch/release roll pin

Other than that, I did the rest of the lower receiver myself.  The pivot pin retaining pin was a real bugger without the special tool.  I was able to use an unsharpened pencil push the retaining pin in while pushing the pivot pin into place, but it took me about six attempts (each time the failure resulted in launching the retaining pin across the room).

Figure 3 – Pivot Pin installation

Be very careful installing the roll pin for the trigger guard, if you hit the tabs it goes into wrong or hard enough, it will break and ruin the lower receiver (it is not repairable).

Figure 4 – The day it was assembled.

As I said before, I’m very happy with the way the gun came out.  Because of the thin profile barrel & Magpul parts, it is a VERY light gun.  I initially considered not adding anything more to it because it was SO light & handy.  No sling or optic or light.  I am very impressed with the Magpul MOE kit.  It’s very comfortable and durable feeling.

As you can see from the current picture, I have added a Bushnell TRS-25 optic, a sling and a Magpul AFG.  I still hope to Duracoat all the black parts into a brown color.  That should be different from most & fit in well here in the Pacific Northwest.  I might change the flash hinder.  But it’s mostly done.  For me, it’s a keeper.  The hard part is going to be deciding which of my kids to hand it down to!  Hopefully you have as good of an experience as I did!

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2 thoughts on “How to Build Your Own AR-15”

  1. Nice job Gilfner! Very nice. Looks like you put together a very serviceable rig. I might add another website to get good parts is Bravo Company.

    They have excellent quality stuff if you are willing to pay a little more. Plus they have great customer service and always seem to be running some good deals.

    I also think they make some of the best charging handles in the biz. I have a couple of them. They are pretty pricey online but you can find them cheaper at gun shops or shows. I think they even carry them at Fleet Farm, if you have those stores in your area.

    Excellent work on that rifle!

    For me, I would add a single point sling adaptor and a Hogue grip….but that’s just me.

    Does MagPul make the best stuff or what? I love their gear.

    Nice work!

  2. Very nicely done.

    I still prefer the Springfield M1A (though everyone in my group are AR fanatics). Guess, I am old school.

    Now it’s time to head to the range or the woods and burn up some powder. Building a new toy is fun, playing with it is even better. Good shooting.


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