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Machine Guns, SBRs, Supressors, Oh My! Complete Guide to the NFA

If you have ever wanted to buy a fully automatic, short-barrelled, or suppressed weapon, you have to first understand this one crucial gun law.

    The National Firearms Act, or NFA, is a confusing part of firearms law isn’t it?

    I know it, you know it, everyone knows it.  Luckily you have me!  And luckily I have the internet, know an SOT, and happen to be going through the NFA process as we speak.  Or as I type.

    ar15 with suppressor
    Who doesn’t want a suppressor anyway?

    Today we are going to try our best to explain a piece of legislature that rules the firearms industry and almost everything they do.  Even if the act itself can be kinda silly at times.

    I’ll try to avoid diving too deep into the legislation, and the legalese.  While there are always pending cases, landmark changes in legislation and ever-shifting policies I will be attempting to explain the NFA as we know it now.

    History of the NFA

    So before we dive into the NFA we need to take a look at exactly why it exists.  The National Firearms Act dates back to June 1934.  The nation was in the middle of the great depression and dust bowl…bank robbers, bootleggers and gangsters were the talk of the town.

    While it’s easy to look back and assume that the hysteria was real it was vastly overblown by an overdramatic media.  The gangsters of the era used a wide variety of weapons including machine guns, shotguns, handguns, semi automatic rifles, and more.  Machine guns like the Thompson SMG and BAR were used by the most famous bank robbers like Bonnie and Clyde and John Dillinger.

    Thompson Sub Machine Gun, Hickok45
    Thompson Sub Machine Gun, Hickok45

    However, they weren’t common with your average criminal.  They were too expensive, and they were often too big and heavy for most criminals.

    The legislature knew they could not outright ban the weapons, but they could apply stringent means of ownership.  This included a registration scheme, a tax, and a buttload of paperwork to deal with.  This effectively made these weapons inaccessible to anyone but the rich and connected.

    At the time the 200 dollar tax stamp was outright ridiculous, and equivalent to about 3,500 dollars today.  In the midst of the depression this would effectively make it impossible to own for a normal person.  Luckily, the 200 dollar tax stamp remained the same, making it relatively affordable for people today.

    thompson smg ad

    So what weapons fell under regulation of the NFA?

    Classes of NFA Weapons

    Machine Guns

    Machine guns, as defined by the ATF are weapons that fire more than one round per pull of the trigger.  This includes burst fire weapons as well.  This also includes devices that can be used to convert a gun to fully automatic.  This devices are regulated and treated like just like a standard machine gun.

    Skorpion Submachine Gun
    Skorpion Submachine Gun

    The most common of these devices being something like the lightning link.  Semi automatic open bolt weapons like some early Mac pistols are also regulated under the NFA if they were produced after 1982 .

    The ATF and the NFA don’t make a whole lot of sense sometimes, in fact they once basically stated that shoestrings were machine guns.  

    Short Barreled Rifles 

    So the law states a rifle is a weapon designed to fire a projectile through a rifled barrel with the use of a stock.  The NFA regulated rifles with barrels shorter than 16 inches.  Any rifle sporting a barrel shorter than 16 inches is a short barrelled rifle. 

    Make sense?

    A short barreled rifle, or SBR, is a handy little weapon to have.  Since the definition never mentioned calibers, or really any configuration besides a stock and barrel length we can own rifle caliber pistols.  AR, AK, and even FAL pistol exist as pistols and not rifles.

    short barreled rifle
    Daniel Defense SBR

    Short Barreled Shotguns

     A shotgun is defined as a smooth bore weapon with stock designed to fire shot.  Shotguns in the United States have to have barrels at least 18 inches in length.  Any shotgun with a barrel less than 18 inches is a short barreled shotgun.

    Some shotguns are also destructive devices, which we’ll cover later.  Because a shotgun is defined as having a stock, or being redesigned to have a stock, certain weapons are not considered shotguns and not bound to barrel length.

    For example the Mossberg 590 Shockwave ($449.00) is a 12 gauge firearm because it has never had a stock.  It’s also longer than 26 inches in length so it’s not an AOW.  Trust me I know it sounds weird, but I’ll try to ensure it makes sense.  Check out our 590 Shockwave Review, if you want to learn more.


    Silencers, suppressors, can, mufflers, or whatever else you want to call them are also treated as NFA firearms.  Are they firearms?  No, but they’re included under the act because of reasons.  Good reasons.  The very best reasons.

    Superlative Arms Full Auto Suppressor
    Superlative Arms Full Auto Suppressor

    A silencer is any devices that reduces the report of a firearms and can be readily attached to a firearm.  Some  folks in the gun community like getting all particular about silencer vs suppressor, but the NFA and the ATF call them silencers, so I’m using their terminology since we’re talking specific legal terms and such.

    Destructive Devices

    This is the funnest category in my opinion.  Destructive Devices, or DDs, are weapons with a bore over .50, except for most shotguns.  This also covers explosives, mortars, missiles, poison gases, grenade launches and other destructive elements.

    grenade launcher

    Some shotguns lose their exemption as shotguns and become destructive devices.  This is usually based around the idea they have no sporting purpose.  The only two shotguns that have made this category I know of are the Street Sweeper and the AA-12.

    Any Other Weapon

    Any other Weapons, or AOWs, is a crapshoot category of weird, odd, and cool weapons.  This includes 12 gauge firearms with an overall length less than 26 inches.

    There are also guns that don’t look like guns like cane guns, some pen guns, and other disguised firearms.

    Shotgun cane

    Oddly enough handguns with forward grips are considered AOWs.  So if you attach a vertical foregrip to a Glock’s rail that is an NFA weapon.  This is due to the crazy definition of pistols that states they are supposed to be used with one hand. Fortunately, AOW’s have only a five dollar tax stamp when transferring.

    NFA Imports

    For some time the foreign market was as a small contributor to the NFA.  There were lots of foreign made machine guns, especially WW2 sub guns coming in pretty cheap.  Often the 200 dollar tax stamp cost more than the guns.

    Then along comes the Gun Control Act of 1968.  The GSA as it’s commonly called was some very sweeping legislation that affected the NFA substantially.  The biggest change was prohibiting the import of NFA firearms.

    The Sporting clause was implemented and that’s why today we can’t import Glock brand suppressors, or factory CZ Scorpion SBRs.  Luckily we can import CZ Scorpions as pistols and convert them to SBRs, and the do the same with AK pistols, and other foreign imported weapons.

    Purchasing NFA Items

    So before you purchase an NFA item there are a few things you need to know.  First none of this constitutes legal advice, and you should verify all the information I provide.  Second know your state’s laws.

    Some states regulates NFA items or outright prohibits their possession in certain states.  So verify your state’s laws before you dive headifrst into the NFA Market.

    atf meme

    Requirements to Purchase an NFA item: Quick List

    • Appropriate Forms Filled and Filed
    • $200 or $5 dollar check or money order.
    • Clean Background check
    • Two Fingerprint forms filled out and submitted.
    • Passport style photograph submitted.
    • CLEO has to be notified.
    • Must be over the Age of 21

    Here’s a few more things you need to know prior to purchasing an NFA item.

    Trust Vs Individual

    You can purchase NFA items as an individual or as a trust.  Some rulings in early 2016 greatly changed the advantages and disadvantages of either purchasing method.  With either method you need to submit photos and fingerprints, and there is no longer a need for the Chief Law Enforcement Officer in your area to sign off on your NFA item.

    CLEO notification

    You do need to alert your local CLEO you are purchasing the weapon, but do not need their permission.

    The main difference is that multiple people can be on a trust.  The benefit of having multiple people means they can all legally have access to and possess your NFA weapons.  As a married man I’d like my wife to have the legal means to use my NFA items.

    If she’s on my trust she can legally possess the NFA items that are also on the trust.  When doing a trust every individual on the trust must submit fingerprints and photos.  The only exception is beneficiaries who will inherit the weapons in case of the death of both my wife and I.

    As an individual I don’t have to invest in creating a trust, but I am the only person who can legally use my NFA items.

    Different NFA forms

    There are several forms within the ATF, that deal with the NFA.  Many relate to dealers, manufacturers, and other industry types.  As an everyday normal Joe Gunguy there are three main forms potential NFA owners would likely deal with.

    You’ll need three of each form filled out.  Two sent to the ATF, one will be sent back to you once approved.  The Third will go to your CLEO to notify them of your pending transfer.

    ATF Form 1

    Form 1 is the fun one, it’s needed when you want to manufacture an NFA item.  Now most of you are likely saying, well I’m not going to manufacture an NFA item.  However, you need to know what the ATF means when they say manufacture a weapon.

    This isn’t you breaking out the CNC machine and creating a brand new gun.  Let’s say you purchase an AR 15 pistol and want to turn it into a short barreled rifle.  All you really need to do is attach a stock and buffer tube.

    However, in the eyes of the ATF you are manufacturing a new gun.  

    It’s crazy right?  Well, that’s just how it is.  

    Here’s a link to the PDF variant of the ATF Form 1, there is quite a lot of slots to fill out, but it’s somewhat self-explanatory.

    You’ll also have to engrave a serial number onto the weapon and either your trust name, or a last name.  It has to also follow ATF guidelines for serial engravings.

    rifle engraved meme

    ATF Form 4  

    The Form 4 is one of the simpler forms.  A Form 4 is used when you are transferring an already manufactured NFA item.  So if you walk into a gunstore, spot a suppressor you like, you’d fill out a Form 4.

    A Form 4 goes through an FFL/SOT and they’ll fill out certain sections and you’ll fill out the rest.  It’s quite straightforward and you can take a peek at an online Form 4 to see what’s required to fill one out.

    ATF Form 5

    The Form 5 is used when the transfer will not be taxed.  There are several situations where a tax free transfer can occur for NFA items.  The most common is a transfer to an heir or beneficiary.

    These transfers can also occur with the transfer of government own NFA items to civilian hands.  Often police forces will sell short barreled shotguns and semi automatic short barreled rifles that can legally be transferred to citizens.

    Recently a few police departments have sold some Thompsons from the prohibition era to fund the purchase of modern AR 15s.

    atf 16inch meme

    For a full list, and a look at the Form 5 check it out here.

    Traveling with NFA items

    So when it comes to traveling with NFA items you need to be observant about a few things.  First and foremost to cross state lines with an NFA weapon you’ll need to notify the ATF via written form.  They’ll approve and return the form and you are good to go.

    You can also get approved for a date range.  So If you are traveling back and forth to a location for say a month, you can apply to travel for that month and be approved.  The only item that is exempt from this is suppressors.

    You also need to make sure the state you are in allows the NFA weapon.  Just because the Federal government says it’s okay doesn’t mean a state government is cool with it.  Now the firearms owners protection act does make it okay to pass through states for the purpose of travel, but YMMV.

    The State of the National Firearms Act

    These days, weapons like SBRs, suppressors, and even AOWs are more popular than ever before.  This has created a lot of support for revoking, modifying, and removing items from the NFA.

    Bills like the Hearing Protection act are actually attempting to deregulate suppressors and remove them from the NFA.  Will these bills pass?  Maybe, maybe not, but if you want to see them succeed certainly contact your legislature.

    The National Firearms Act is an ancient piece of legislature, but one that certainly affects our lives.  I’d love to know what our readers think, and what their experience with the NFA is.

    Where do you stand on bills like the Hearing Protection Act?  We’d love to know.

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    9 Leave a Reply

    • Commenter Avatar

      Can someone give me a concise update on this issue regarding buying a MCK from a manufacturer?

      January 15, 2023 12:09 pm
    • Commenter Avatar
      Joshua Burns

      If I'm reading this article right, if I want to buy a Fostech short barrel shotgun, all I have to do is fill out and submit Form 4?

      December 29, 2019 10:23 pm
    • Commenter Avatar


      Crazy question which probably was answered already.

      I built an AR15 pistol, I would like to change it to an SBR. Can I apply for the tax stamp, and then make the changes? Is it that simple or more complex?

      Any advise would be appreciated.


      November 4, 2017 11:32 am
      • Commenter Avatar
        San Tan Armory

        Simply fill out and submit your Form 1 with everything necessary, wait until you get your approved form back in the mail from the ATF with the Stamp on it then you can throw your stock and vertical foregrip on it and have your lower receiver engraved with the serial number and city/state on the Tax Stamp.

        June 6, 2018 10:41 am
    • Commenter Avatar

      I didn't notice that you said anything about the atf's change in stance in shouldering a brace, if I run a sbr with a brace should I be worried about an issue, The only place it maybe seen is at the range?

      August 22, 2017 1:45 pm
      • Commenter Avatar
        Eric Hung

        Yes they did reverse it but you never know with range officials or police at the range who aren't up to date. I try not to shoulder it at public ranges.

        August 23, 2017 11:27 am
    • Commenter Avatar

      Great article. Our firearm laws, like our tax laws, are probably purposely made to be somewhat confusing. They are, at times, rather vague. This, I surmise, is to allow the gov't. a bit of "wiggle room" when they go after some poor individual who has a 15" barrel on his AR, for example. His 'flash hider' is 1.5" so the barrel is legal length, but he forgot to either pin it or weld it so it's permanently attached.

      July 28, 2017 2:35 pm
    • Commenter Avatar
      Josh Jencks

      I'd like to see the hearing protection act go thru. Been waiting and hoping

      July 27, 2017 5:05 pm
      • Commenter Avatar
        Eric Hung

        Fingers crossed!

        August 6, 2017 2:04 pm
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