In an entirely unexpected turn of events, ATF has reclassified completed and even so-called “80% lowers” with a fake auto sear marking as machine guns, depending on who makes them. Here’s an image of one such receiver the Bureau has taken custody of and ordered destroyed.

The problem is that fake sear hole. Marking such a receiver with a small, engraved ring has been one detail adopted by detail-obsessed retro builders for years. The receiver above is a typical example of this detail obsession. It began as a so-called 80% blank, and has been completed to firearm stage. But it also has been engraved with Colt markings and extensively machined to change its profile from the current reinforced lower to the M16A1 vintage shape, especially in the vicinity of the pivot pin bosses and the buffer tower. Internally, the receiver remains AR-15 semi-auto profile only, and cannot accept M16 full-automatic parts.

High-pocket AR lower (l.) and M16 showing auto sear and more open receiver (r).

Under this novel, stretching interpretation, this 80% receiver blank, too, is probably a machine gun, even though it is not completed. No trigger group machining has been done, and it cannot accept machine gun (or any) trigger group parts.

There is no consistency to these rulings, and ATF lawyers insist that every ruling applies only to the single case at hand, which must be considered de novo, and that previous rulings are not precedent or even evidence. ATF lawyers will take you to court, and will fight to keep their own agency’s prior determinations out of that court.

The ATF has even given written approval to this engraving — when it’s done by large licensees who can afford lawyers to haggle over ATF rulings, like Colt and Troy:

(Troy has taken hits from the market before for hiring a disgraced ATF figure, and some infer an unusually cordial relationship with ATF management. The Troy receiver also has a couple of unique features, which are discussed below).

ATF has also approved the marking in the past, in letters to individuals and licensees, when it is out of position relative to the factory location of an auto sear. But the same engraving now, and done by or for a little guy who has no practical defense against an ATF attack? Strengstens verboten. 

When the definition of an object depends not on what it is, but on who you are, is it really law we’re talking about, or just power? Are we operating under a system of laws that claims derivation from the US Constitution, or under Hammurabi’s Code, which provided “different spanks for different ranks”?

This whole affair began during a routine inspection of US Anodizing in Virginia. All licensees accept such inspections, during which ATF inspectors or occasionally agents examine paperwork, inventory, and overall regulation compliance. Generally these are cordial and professional, but given the weak firearms knowledge of many ATF personnel, and its politics-first pursuit of gun control enthusiast personnel, sometimes they lead to disagreements or disputes. (And some licensees screw up; nothing thrills the ATF more than the chance to hammer a licensee, the bigger the better). On this particular inspection, there was no tension and no suggestion that US Anodizing was doing anything wrong, but ATF initially set several lowers in-process aside for further review. The inspector made a tentative determination that lowers completed from so-called 80% lowers, and showing any indication of a mock auto-sear pin anywhere on the side of the trigger group, was a “machine gun” because it would be “readily convertible.” That’s even in the case of a firearm that would require considerable internal machining to accept MG parts.

There were relatively few receivers — more than three but not more than six — with such a marking on site, but others may have passed through in the past, given this feature’s popularity with retro-heads.

The ATF actually hasn’t seized the receivers in legal terms. Instead, it is holding the receivers and has demanded that the owners voluntarily surrender them to be destroyed, or face prosecution. They say that this is a generous offer that they don’t have to make but are willing to do because they have determined that there was no intent to violate the law.

But, and here’s the rub, they’re demanding that the owners not only allow the ATF destroy the receivers, but also, that they sign a sort of Chinese-show-trial-confession letter, admitting having produced an “unregistered machine gun.”

UPDATE: The following was received from the owner of the 1st receiver illustrated above:

The 1st pic is of my receiver. I am one of the 6 or so that have had my receiver seized. I must tell you that this part :

But, and here’s the rub, they’re demanding that the owners not only allow the ATF destroy the receivers, but also, that they sign a sort of Chinese-show-trial-confession letter, admitting having produced an “unregistered machine gun.”

…is not true. I, at least , have only been given an ATF Form 3400.1. I have NOT been asked to sign anything admitting to creating anything or breaking any laws.

We stand corrected and have lined out the paragraph in question. Form 3400.1, Property Taken into Bureau Custody, is used in nonjudicial takings. It describes the property, and the person or entity from which the property was taken, but does not require or expect any admission of anything. This OIG report of some of ATF’s problems (.pdf) managing seized property in the 2004-05 period shines some light on the regulation in question, ATF 3400.1B. ATF takes approximately 200,000-300,000 items a year, of which about 10,000 to 30,000 have historically been firearms.

The owner of the receiver in the first illustration above decided to sign the ATF letter and let his “machine gun” be destroyed; others, who are not in the crosshairs of the ATF like he is, have criticized him for “caving,” but his choices are (1) give the ATF the Cardinal Mindszenty confession uncontested, nonjudicial surrender-of-property that they want, or (2) fight, with the possible outcomes of: (2a) a pyrrhic “victory” that would leave him a financial ruin after years of stress; or, (2b) a decade of two in Club Fed.

Of course, given the legal constraints and historically demonstrated character of the ATF as an institution, you can choose (1) and get (2a or 2b) also, if they feel like making an example of you.  Today. For something they approved for Harry yesterday and will approve for Tom tomorrow.

It is hard to fight this kind of creeping, arbitrary, whimsical regulation. Under most US regulatory law, the courts defer almost absolutely to the regulatory agency. As we understand it, and we’re not lawyers, court precedents rule that the expertise on any particular regulatory area is contained within the regulating agency.

There are social and organizational dynamics at work in the current regulatory environment. Once a field agent or inspector makes such a allegation, it’s the instinct of the Firearms Technology Branch to produce whatever it takes to support the ATF officer and keep him or her from losing face, even at the cost of the FTB’s and the Bureau’s reputation for consistency and even integrity.

ATF argues that Colt and Troy are doing something slightly different. For example, Troy’s receiver has a bridge between left and right sides, and is engraved REPLICA – SEMI ONLY for those law officers not steeped in firearms design and construction. But the real underlying problem is baked into regulatory law: there’s no reason that ATF can’t argue the law any of several different ways in different cases at the same time.

We see this ATF power grab casting a chill over the retro movement, which is a small and relatively inconsequential. But the bureau’s real target is the “80% lower” builder in general and the entire home gun building movement, which senior managers and the Chief Counsel’s Office would like to criminalize. This is one of the things that senior managers such as Thomas F. Brandon, who put the ATF behind the Hillary Clinton campaign in major newspapers, was hoping to get out of the Administration they wanted. (Wanted and expected. They had initiatives ready to go).

This is a legal minefield and anyone in this position needs a professional and experienced attorney (i.e. experienced with the ATF and with Federal gun laws).

This entry was posted in GunTech, Lord Love a Duck, Poly-Ticks, Weapons Education on by Hognose.

About Hognose

Former Special Forces 11B2S, later 18B, weapons man. (Also served in intelligence and operations jobs in SF).

45 thoughts on “ATF Cracks Down on Retro Builders using 80% Receivers


What’re the chances of getting this on Fox and in President Trump’s sight picture? One more EO ordering one of his Executive Dep’t agencies to straighten up would start to reign them in. If they want to play Judge Judy and executioner then they have to establish case law and precedent and it has to be admissible.

John M.


“which is a small and relatively inconsequential.”

Strike “a”.

-John M.



John M.

Isn’t the “80%” part of “80% lower” ATF reg (i.e. not Congressional statute)? And likewise what defines “80%” vs “81%”? So couldn’t ATF change either reg pretty much whenever it wants, subject to the usual NPRM? (Granted, the first 100 days of the Trump administration might not be a good time for this, but why didn’t they do it in 2013, say?)

And for my money, the best way to get this to President Trump’s ear is to take it to Don Jr. or Eric. They are gun guys-from what I hear-and will understand the issues and can bring this to the President in a way that makes sense to him.

-John M.


I thought the 80% thing wasn’t anything official but just a marketing gimmick that became its own standard.

Hognose Post author

Yeah. FTB will examine a part and tell you if it’s a firearm or not. That’s all. Go or No Go, no percents.


Donald Jr. I know has participated in Highpower matches in the past with an AR.


Let’s just get the Hughes Amendment repealed and we can all build a machine gun and register it.

After all, the Full Auto LPK are available on the Web. If you know where to look.

Raoul Duke

Different verse of the same old song.

Consider the case of select-fire M2 .30 Carbines: ATF ruled a long time ago that if a receiver was engraved as “M2”, that made it automatically a machinegun…EVEN THOUGH THE RECEIVERS ARE FUNCTIONALLY IDENTICAL IN EVERY DETAIL to semi-auto M1 receivers.

This rule was applied to all receivers, even those newly-manufactured. Therefore, an engraving in a piece of steel is EVIL and ILLEGAL.

Let’s not bother mentioning the Akins Accelerator, or numerous other changes-of-regulatory-heart that have happened.


I thought the Prez had specifically put an EO hold on all regulatory shenanigans (which is actually fairly standard when a new administration rolls in).

Mr. Chubbins

Curious, very curious. Thinking out loud:

On another site there is a post on ATF cracking down on home build suppressor component sales, and now this. Makes me think that ATF is trying to drum up relavance due to the renewed effort to fold them into FBI. At first I thought ATF was going after suppressor parts due to HPA taking a bite out of that lucrative enterprise, but now with this additional nonsense, a play for continued existance is more likely. In which case, hang on tight.

Hognose Post author

And keep the dogs and cats indoors.

Cap’n Mike

I was optimistic that the ATF was shifting in the opposite direction for the new administration and shifting there attitude to helping gun owners, at least for the next 4 years.

I thought this was the case because on January 17th, before Trump was even sworn in, The ATF started approving tax stamps again for the state of Massachusetts.

They had been sitting on them since July 20th, when State Attorney General Herr Healey issued her royal decree on “Assault Weapons”, leaving ATF unsure if issuing SBR tax stamps violated Mass State Law.

I had hoped this was because they saw the writing on the wall about the new broom being inbound.

Sucks that they are still doing this type of piddly shit.


Just another example of what’s wrong with government at all levels: arbitrary, inconsistent, politically driven decision making that we as the citizenry have no control over and no judicial response too. A sure sign of the decline of the republic.

Keep your powder dry and your faith in God.


Legally, trace marking of the automatic sear pin location is indistinguishable from having ‘AUTO’ stamped on the outside.of an AR receiver in the selector sweep area. Court tests of what constitutes a ‘machine gun’ legally have always required ATF experts to create a functioning machine gun by parts assembly or parts removal only – no dimensional modifications.

This overreach by the ATF Office of the Chief Counsel will be defeated in its first serious court test.


I was trying to look at this from their point of view by saying it was a template for installation of the sear assembly. The only thing I came back to with that thinking was their so-called constructive intent garbage which is in the same legal textbook as the “she was asking for it” rape defense.

Wasn’t there a similar debate many years ago over the high vs. low shelf lower receivers?


There are, in fact and practice, two divisions of BATFE: they are Arbitrary, and Capricious.

Everything they do has to have approval from one, and ideally both, divisions, before it gets handed down from on high as verbum dei.

For some decades, that hurdle has not been too cumbersome on their limited intellects to allow passage of all manner of nonsense, being a speed bump the height of which is measured in layers of paint on a flat surface.

Give their explosives lab to FBI, shift alcohol and tobacco revenue collection (sans any law enforcement capability whatsoever) over to Commerce, and fire everyone else, or simply transfer them to baggage screeners for TSA to make retirement. Ideally in airports not less than 500 miles from any city larger than 1M souls.

Josey Wales

”Give their explosives lab to FBI, shift alcohol and tobacco revenue collection (sans any law enforcement capability whatsoever) over to Commerce, and fire everyone else, or simply transfer them to baggage screeners for TSA to make retirement. Ideally in airports not less than 500 miles from any city larger than 1M souls.”

That’s actually a really good plan…..


While I try to stay glib and pithy, I really do think about this stuff.

I just can’t get the required signatures for Emperor For A Day.

Tom Stone

To answer your most important question, yes there are different spanks for different ranks.

The Rule of Law based on the Constitution was abandoned some years ago.

How many examples do you need?

Holder, Petraeus, HRC….I could fill a LOT of pages.

John M.

They told us it was “the Rule of Law.” It turned out that it was always intended to be “the Rule of the Progressive Elite.”

-John M.


The other funny thing ATF has done is the is the prohibition on shouldering a pistol stabilizing brace

This is only an opinion letter issued by the ATF

No one has been arrested and no Judge has ruled on this issue

So far this is just an opinion from them and everyone can keep shouldering their Sig brace and blasting away

At least until they arrest someone and try to get a ruling from a judge in a court


IIRC, the brace is not even required to create a problem. Shouldering the pistol buffer tube is can be construed as repurposing or some such nonsense.


“A chicken in every pot……..and a completed 80%’er behind every door” Let’s make America great again


Would the FBI really be worse than the ATF when it comes to this kind of garbage?

I still believe that the memory of an entire Federal agency disbanded because of a history of incompetence and abuse would provide a useful nudge to the behavior of other Federal agencies which remain.


You want to really make an impression…?

Fire every employee, ban them from government work ever again, and cancel all pensions to former employees-After all, they selected, trained, and promoted the over-reachers in the first damn place.

There’s a root-and-branch issue with the ATF, I’m afraid-The explosives and fire investigation bits of the agency are decent, from what I’ve heard and seen of their performance, but the rest? Rooted in the corruption of the Prohibition, and never managed to overcome that. If I’m not mistaken, this is the same agency that approached the Prohibition by poisoning grain alcohol supplies so that citizens would die from imbibing… It needs to be the first victim of a “corporate death penalty” for government agencies.

Leave the retirees in poverty, and fire the rest as a salutary lesson to others.


Uh, while an enjoyable day-dream, virtually none of those suggestions are plausible, and some of them wouldn’t stand up to judicial review if they did happen.

Obviously disbandment of the ATF would have little value if the organization as a whole were merely absorbed into the FBI. But if the ATF were disbanded and the responsibilities for enforcing firearms laws transferred to the FBI without an increase of budget or personnel, that would still have a major impact, and still comply with the civil service laws.


The fact that none of those suggestions would actually come to pass under the current system is a huge contributing factor to why we likely won’t keep our Republic.

When you have IRS officials that are completely unaccountable to the Congress, when you have agencies like the BATF conducting things like Fast and Furious, and then lying about it…?

Things like that are the very definition of unaccountable. And, without some mechanism to quite literally kill the agency, they never will be. And, given the fact that the retirees of such agencies are the ones who recruited, trained, and promoted their successors who performed these rapes of rectitude…? They need to be called to account, period. Putting them into poverty in their old age would be a salutary lesson to the rest of the bureaucracy, and one that would only be fair-After all, how many people did the men and women they selected, trained, and promoted did the exact same thing to their fellow citizens?

No, if you want to rid yourself of the creatures that manned the Stasi and the Gestapo in your own society, you have to make the penalty for violating the rule of law sufficiently damaging to transgressors that they would prefer not to participate in the extra-constitutional things that result in their agency being executed.

Corporations should be held to the same standard; you want to sign off on something like what VW did, where the malfeasance was a known and documented thing? Confiscatory measures should be taken, and your opportunity to benefit from employment at that corporation should be ended, to the point of the pension plan being taken away, if justified.

We have the death penalty for truly egregious criminals. Similar measures should be in place for corporations and agencies, if they are collectively going to be given the right to act as individuals under the law-Which is precisely what the Congress has done, by sloughing off responsibility for writing regulations onto these agencies. So long as individuals are able to hide beneath the wing of selective immunity, this crap is going to go on. And, if it does, the Republic will eventually die, choked to death under a mountain of petty bureaucracy.

John M.

The VW malfeasance goes straight to the top. Quote from Ferdinand Piëch, per Bob Lutz:

“I’ll give you the recipe [for better body panel fit]. I called all the body engineers, stamping people, manufacturing, and executives into my conference room. And I said, ‘I am tired of all these lousy body fits. You have six weeks to achieve world-class body fits. I have all your names. If we do not have good body fits in six weeks, I will replace all of you. Thank you for your time today.’ ”

If you create a culture like that, then you create a culture of shortcuts, cheating, and yes, to reference yesterday’s thread, careerism.

-John M.


The FBI is limited to what it can get a jury to bite on. Witness the Malheur mass acquittals.

BATFE spews (contradictory, arbitrary, and capricious) regs out as God’s Holy Writ, because Congress finds it easier than having to try it themselves, and getting voted onto unemployment for their sins, contrary to original intent.

Hognose Post autho r

Just read something interesting about one of Trump’s XOs. Reportedly, he has directed the government’s agents to settle all questions of interpretation more favorably to the individual citizen than to the government. Will try to find the source doc tomorrow and see if it actually says that.


BATFE- making it up on the fly since, well, forever.

This is really a bunch of crap. A lightly engraved mark on the side makes it a machine gun? That’s on a level of stupid equal to the shoelace ruling.

The problem is that no one really stands up to these arbitrary rulings because it costs a ton of money and you’re going against the infinite checkbook of the Even if you win, you lose. Given a settlement offer to confess your guilt or spend your entire life’s savings, plus that of everyone in your family, yet still have the chance of going to federal prison because the judge is a moron, who’s going to take that?



Silence Dogood

The ATF has only one job, to perpetuate itself, like all government. The BATFE is only the latest in a series of name changes and legalistic sleight-of-hand that has kept the original Federal Alcohol Administration going since declared unconstitutional in 1935. ATF was NOT authorized by Congress. It is a branch of IRS / Treasury, and it’s jurisdiction ( if any ) is limited, if the law is followed. It has a very sketchy legal standing.

Time to ABOLISH the BATF , and modernize laws. ; Much more at link. ( Legal speak made plain )


Someone should take picture of the top dogs at ATF, photoshop some screws in their ears and text around the mouth “FULL AUTO ATF HOLE”.


My last name has an “O” in it, what if when doing my ATF required markings it happens to fall in the same location? What then Mr. Agent Man?

Hognose Post author

Then you are an unregistered machine gun and must submit yourself for destruction.


You will be told NOT to have ANY markings in that area.

The 1st pic is of my receiver. I am one of the 6 or so that have had my receiver seized. I must tell you that this part :

But, and here’s the rub, they’re demanding that the owners not only allow the ATF destroy the receivers, but also, that they sign a sort of Chinese-show-trial-confession letter, admitting having produced an “unregistered machine gun.”

…is not true. I, at least , have only been given an ATF Form 3400.1. I have NOT been asked to sign anything admitting to creating anything or breaking any laws.

Hognose Post author

Thank you for this important correction. When I get back to the office I will make a correction in the post proper.



…suddenly there came a tapping,

As of some one gently rapping, rapping at my chamber door…

Windy Wilson

Yep, those are all machine guns, they are machines that are guns.

What a disgusting case of barracks lawyering by a federal agency that should know better!

What a load of codswallop!

What a load of . . . (well, I won’t say, exactly, you may desire this to remain a family-safe blog.


THIS is why, even though I’m more than capable of fabbing basically everything I’d need myself, I’ve always stopped short of doing myself up a closed bolt but striker fired and more or less 100% accurate M231 clone. (I’ve even got a shit ton of PDF documents mostly from small arms review online archives of experimental alternatives / replacements for M16 iron sights I used to gin up some bitchin and totally era correct looking options I worked up in Inventor!)

Stuff like this is also why I resist the urge to do a 231 length buffer tube gun with a transplant under folder AK stock adapter that when unfolded automatically unlocks a bumpfire option…

(The ATF makes my inner Khyber pass rock star reality TV gunsmith depressed)