Ask Foghorn: Best Self Defense AR-15 in 5.56x45mm NATO?

Mike asks:

I am new to AR-15s. Then only rifle I own is a Marlin .22. I was interested in getting an AR-15 and was reading your “Best Self Defense AR-15” article. If you were to build a similar AR-15, but wanted to shoot 5.56×45 what would your build look like?

I’ve had a couple requests for this, and so I’ll let you in on my winning design (in my opinion, at least) for a self defense AR-15 in 5.56 that you can build yourself for about $1,300…

The picture above is more or less my “perfect build,” but it used the wrong lower and optic. Back in college I built this AR-15 to compete in the Limited division of 3-gun competitions, and the what made it ideal was that it used the same lower receiver as my competition rifle but a different upper receiver. I still have the upper kicking around somewhere in my closet, but since my infatuation with .300 BLK began it has taken a backseat.

With the benefit of hindsight and MUCH more experience than I had back then, this is the parts list for the “perfect” self defense AR-15 in 5.56x45mm NATO:

Total build: $1,328 + tax + shipping.

You may notice that the lower receiver is basically the same as my .300 BLK build, and that’s because I like the way that lower works for a nimble rifle. But let’s talk about why I made a couple of the decisions I did in the build to alter it from the .300 BLK configuration.

The first thing that should jump out at you is that the upper receiver doesn’t have a free floated barrel. The reason behind that design decision is more about saving money than anything else, as free floated handguards can cost a pretty penny and standard handguards will provide enough accuracy for self defense situations out to at least 50 yards. Plus, they make maintenance a lot easier (as they’re faster to remove and replace than the free floated kind).

The next thing that might catch your attention is the red dot sight. Why use a cheap dot instead of a complex holographic sight like an EOTech? Because it’s simple. Put the dot on the target, pull the trigger. It’s dead simple, small enough to not obstruct much of your field of view, and above all else CHEAP!

The last interesting design decision is probably the fixed front sight, and that’s mostly because (once again) it’s cheaper to do it that way than a flip-up sight on a low profile gas block. After years of using this upper, I can tell you that the fixed front sight doesn’t really get in the way all that much once you set up a red dot and start shooting with both eyes open. Plus, to me it just looks… right.

The only thing I might suggest to improve this gun is the addition of a silencer. 5.56 is an extremely loud round (especially in confined spaces), and the ability to hear during and after a DGU will be very beneficial, either in detecting additional threats or trying to explain the thing to your lawyer. That’s the reason I like .300 BLK over 5.56 — the ability to completely suppress the sound of the gun and the bullet. But if you’re dead set on 5.56 this will do the job.

If you’re unwilling to build it yourself (or just too lazy) here are a couple of complete rifles that will get you close:

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