DIY AR 15 build—The project begins

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by Rob Kay and RN Price

Protect with tape but don’t use duct tape (like we did) (photo by RN Price)

Finally the moment we’ve been waiting for. The actual build out.

Ok, lets cover the necessary tools.

You don’t need special tools but it really helps to have some basics such as a set of roll pin punches (especially the type with the hollowed-out tip that are used to install roll pins), a light hammer, a set of vise grips, a long Phillips screw driver, electrical tape, needle nosed pliers, a flat screw driver, and a set of Allen wrenches (3/16th” in particular) also come in very handy. You’re also going to need an ARmulti-tool or castle nut wrench (for carbine receiver extensions).There are also special gunsmithing tools such as a lower receiver block which can help keep your receiver stationary, but you don’t have to have it. Most everything else can be improvised.

A few introductory notes…Roll punches come in handy. These are the black ones on the left with the dimple. A standard punch is flat (see below) so it’s advised not to use them, even if you have one at home.

You’re going to need roll pins (the black ones with the dimples). The one the right is not a roll pin.

We’re not going to try and reinvent the wheel when it comes to this project. A lot of people have written about a DYI build. Some better than others. We simply want to pass on what we’ve learned. There are some really good videos online and we’ve posted links for the ones that we think you’ll find useful.

Getting Started

The first thing we did was to sort out the various LPK parts. In most instances they come in color-coded bags. In the case of the Stag LPK, all the parts were jumbled in one bag. We sorted them out the way you might the pieces of a jig saw puzzle, before you start to put it together. It was a good exercise in getting to know our LPK.

LPK lower parts–you’ll want to get to know them well

This shot on the right (courtesy of AR will help you identify the various parts.  Believe me, you’ll get to know them all intimately.

So what component do you start putting together first? If you go online and check out the videos and instruction manuals you’ll see that there is no ironclad rule dictating the order in which the LPK parts should be installed. However, in the interests of simplicity and making the build as straight-forward as possible, you will come to see that some things should be installed before others. The order shown here was chosen with this in mind.

So let’s get started.

Installing the Magazine Catch

First off, place some electrical tape on the right side of thereceiver to protect it. It’s really, really easy to deface yourlower. We don’t recommend you use duct tape. We tried and it left a nasty goo behind when peeled it off, forcing us to dig out some acetone to clean up the mess. Electrical tape leaves no residue.

Depress the match catch button hard and twirl away with the left hand (photo by RN Price)

So back to the task at hand.

Pop in the mag catch on the left side of the receiver and place the mag catch spring from the right side. Then take the mag catch button, push it in and twirl the mag catch until you’ve threaded it flush with the end of the threading. You’ll have to push the mag catch button in a bit beyond what you normally would in order to have enough clearance to spin the mag catch to get the threads deep enough in the button. After you’ve finished, pop in a magazine and see if it locks in place, and then can be released. We’re going to use Cheaper than Dirt videos to help illustrate things. The voice narration sounds a little like an automaton, but the videos are clear, short, well produced and to the point.

Installing the trigger guard

Using the roll pin to gently install the trigger guard. (Be careful not to break off those delicate ears)  photo by RN Price

This is also pretty simple. However, you have to be careful not to break off one of the “ears”. Always keep the lower supported when installing the trigger guard roll pin. Use a soft wood or something similar to support the lower when driving in the trigger guard roll pin. Make sure that the trigger guard is in place too, otherwise the upper ear can break off while you’re tapping on it. Here it really helps to have the right tool, a roll pin insertion punch. The video here is one which illustrates the installation of an aftermarket Magpul trigger guard but the technique is same when it comes to installation:

General note about roll pins: these things can be evil. Most of the time they are well behaved, but they can cause trouble far greater than their size might otherwise suggest if taken for granted. When installing them, make sure that the end of the roll pin that you choose to insert in the hole on the firearm is smooth and rounded. Sharp burrs are bad, as are squared off ends. If necessary, round off the sharp surfaces on the end with a file or a stone. Then apply oil to the roll pin so that it will take less force to push in. You’ll be glad you did.

Use a punch to align the bolt catch when installing

(photo by RN Price)

 Installing the Bolt Catch assembly. 
Be sure and tape the receiver on this exercise. Tap the roll pin in just enough to get it started—don’t tap it too much so that the pin starts to protrude from the other side of the hole.
It’s a good idea shove another punch through the opposite side and align the Bolt Catch assembly. As you tap the roll pin in (or you can use a pair of vise grips with taped jaws to squeeze the pin into place); just make sure you’ve lined it up carefully. Makesure the mushroom shaped bolt catch detent is facing up. One littletip. We installed both the Stag and CMMG bolt catch assemblies with noproblem. I was ready to do the fancy billet from Franklin but for the life of me, couldn’t find the teeny little detent anywhere. I called Dave, the tech guy at Franklin and he gave me some good advice. The Franklin set was wet with protective oil (a good thing). Sometimes, he said, parts will lodge themselves inside a another part with a hollow interior such as the buffer pin. He was correct. After some probing and shaking, that elusive mushroom-shaped bugger appeared.
To be continued!

Questions?  Comments?  Contact us directly at

Rob Kay writes about firearms for Hawaii Reporter and is the author of How to Buy an AK-47.
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  1. Thank you for the informative article. I recently purchased an AR stripped lower with a lower parts kit…so your article was just in time to assist me with its assembly. Well written, good links to video. I liked it so much I save to my bookmarks. I'll visit you again. Can't wait for the follow up articles. Aloha! rb

  2. Your this tutorial is amazing to have these tools to assemble AR 15. Also the YouTube links are more helpful to know the exact way to do all these. Thanks for sharing this article as I found it helpful to solve my problems.

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