You Probably Don’t Want to Convert Your AR-15 to Full-Auto

Dutch opening up with a full auto M16  after the death of one of his squad members in the movie Predator.
Admittedly, this movie probably wouldn’t be as cool with semi-autos.

Full auto…for some, it is the ultimate fantasy upgrade for America’s favorite firearm. 

A surprisingly common yet slightly jarring question we hear at AR15BuildJunkie from first-time builders VERY new to ARs is “How do I make my AR-15 full auto?” 


The short answer for a majority of first time builders is going to be “You don’t.”  Well, not with out a commitment of time, paperwork or money, anyway…

But you really want in on the machine gun fun…your new build is a bit basic and you want to kick it up a notch.  You need the giggle switch.  We get it, but it’s really not all it’s cracked up to be. Frankly, in most situations, sustained and accurate fire with your new build is going to be a much better option for you.

Good info from Bill Blowers on the reality of full-auto. Be sure to check out our recent interview with Bill if you haven’t already.

Step One:  Avoid Prison

First off, we must be explicitly clear, making your new AR-15 build into a machine gun…it’s not something you’d ever, ever think of doing yourself.  Doing so is a good way to end up in federal prison for a long time.

Prison sucks.  Trust us, it’s just not worth it.  The BATF will happily ruin your day, week, year and decade…and your financial future. 

Robert Z’Dar…R.I.P


Step Two: Be Rich

This is so important it needs to be said twice.  Don’t do it. 

Of course, all of our readers are upstanding citizens, and what you want to really want to know is how do you LEGALLY convert your AR-15 to shoot full-auto. 

Again, you’re probably not going to be able to…not without very deep pockets, anyway.

For most, to do what you are wanting requires you to buy a small item that has gotten very, very expensive over the years due to a 1986 ban on new manufacture.  The part is called an auto-sear…and well, these just aren’t floating around in the parts section of your favorite parts retailer.  Unfortunately, there are a limited number in private hands. 

It may help to visualize a pool…one that is rapidly drying.

Compared to building your own AR, finding, purchasing, and dealing with the somewhat complex paperwork required to own one of these moon rocks is probably not worth the time.

Sadly, due to the scarcity principle, you’re looking at dropping easily $30,000.  Probably more.  By the time you read this, you can probably tack a few extra thousand on.  Due to these unfortunate high costs, you might be better off buying an actual Colt M-16 lower.

If you are really wanting to move forward…there’s also a few other routes you can take. Ryan Cleckner explains options like “becoming a Class 3 SOT with a Dealer License or a Class 2 SOT with a manufacturer’s license.”

Step Three:  Be Very Patient

We won’t get into the nuts and bolts of the NFA process or how the NFA itself should be abolished…as there as there’s plenty of great web sites have that info, but the basic gist, as it stands today, involves specialized dealers, forms, fingerprint cards, tax stamps, background checks and a somewhat painful wait that can easily exceed six months. 

Please don’t get too discouraged…it’s not nearly as bad as some people claim, but it does take a level of patience that you may not be used to or comfortable with if you are somewhat new to firearms. That said…if it’s something you are truly passionate about, please by all means, go for it.

Step Four: Realize There’s No Refunds

Now, let’s say you legally acquire that $30,000+ auto sear…you’ve jumped patiently through the annoying NFA hoops, you’ve configured your AR properly with the other necessary parts, and take it to the full-auto friendly range.

The first mag dumps like a dream.  So does the second.  Your grinning uncontrollably from ear to ear.  You slam home mag number three…and it’s then that Murphy’s Law strikes. Something goes horribly wrong…your sear breaks. 

No big deal.  You’ll just get it fixed or replaced.

Maybe.  Probably, even.

But it’s a bit of a gray area, and there’s a possibility that if it is damaged beyond what is repairable, you might be out $30,000+.


Step Five: Realize it’s Not Always Real-World Practical

Is full auto fun? Yes. Very fun.  Is there anything cooler?  Honestly, no, not much. But do YOU ever need it?  Almost never.   That said…I try to never say never. If your foxhole is being overrun, I can see needing to flip the switch.  But frankly, I’ve never seen a foxhole, let alone been in one awaiting imminent human wave assault.  Nor have I needed to clear a room in a combat zone or needed fire superiority to break an ambush. That said, quite obviously it IS a Bill of Rights…not a Bill of Needs.

My ONLY point being…from a strictly real-world, practical perspective, most professionals would agree…there’s usually just simply no replacement for steady, well placed, accurate fire.  In that same real-world, there is just very likely little chance you will need to lay down large volumes of fully automatic fire.

I’m not a military/LE guy, but the first-hand word I hear is these folks almost never need to flip the switch…As such, you’re not really missing out on some key, absolute must-have feature.

This really is just about the coolest thing in the entire world.

Final Step:  Accept That Your Build is Probably Fine As-Is

There’s never been a better time to build your own AR.  Options are limitless.  Prices are thankfully cheap.  Ammo is prevalent (for the time being).  Understand that the firearm you are building is versatile and can do almost any task as well as its full-auto counterpart…for tens of thousands less. 

Perhaps take a few grand you were going to toss into the upgrade and buy an extra few thousand rounds take a few in-depth carbine classes with your new build. Or build something different and uniquely bad-ass…maybe a mini-RECCE or something. Hell, for “wow factor”, why not go crazy and buy that $4,500 dollar Schmidt & Bender 1-8×24 PM II ShortDot Dual CC?

Spike's Tactical SBR
Spike’s Tactical SBR…almost as cool as full auto and about $35,000 cheaper.

But, for those with some patience, no fear of legal paperwork, and/or 30-40 grand burning a hole in their pocket, please don’t let this article dissuade you. Full-auto is exhilarating and an incredible amount of fun.  But again, not doing it legally is unthinkable. 

Finally, if the high cost of going full-auto has you depressed and you’re not wanting to obtain your Class 3 SOT with a Dealer License or a Class 2 SOT with a manufacturer’s license…please don’t despair.  You can still do some very fun and comparatively inexpensive builds involving extra paperwork without a majority of the extra costs associated with full-auto…specifically by diving head-long into the incredibly fun world of short barreled rifles (SBRs) and suppressors…it’s something to consider anyway as you decide if your full-auto dream is one worth pursuing further.

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Craig

No law may stand in contravention to the Constitution. All ‘gun control’ laws are un-Constitutional. Article 6, U.S. Constitution, “The Constitution…shall be the supreme law of the land”. Therefore, no legislative ‘law’ may limit, change, deny or curtail the Constitution, regardless what any anti-American activist ‘judge’ may say. Also in Article 6 “All laws must conform to and be made in pursuance of the Constitution”. Therefore, any law not in 100% harmony with the Constitution is null & void. Americans could own anything they wanted until Congress feared the WW1 veterans and had the 1934 NFA enacted. The SCOTUS, in… Read more »

Huggy

Preaching to the Choir, My Friend. We need to continue to vote OUT all those who would work to dismantle and destroy the Constitution and Bill of Rights and work to ensure their ilk NEVER has a say in causing the kind of grief we deal with today!!

Huggy

I have fired an M16A2 in S/A and F/A and, yes (!!) it is a HOOT but especially wasteful in terms of ammo expenditures! I mean REALLY, TRULY, WASTEFUL! But as the saying goes it is about the MOST fun you can have with your clothes on. Trust me. I have plenty of experience in both categories. All that aside, this guy isn’t made of money nor do I have a Sweetie who happens to be my Sugar Momma, daggnabitt, so S/A it is and will (probably) remain until I win some ginormous LOTTO! Still, the Giggle Switch, the Go… Read more »

Lance

A slick alternative is a binary trigger. I have a BFSIII and love it. Great for double tap, or suppressive fire. Love that I now have a legal 3rd position.

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