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April 02, 2014


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If you define the receiver as a "pistol" when you build it, you can later add a longer barrel and a butt stock (in that order) and all will still be right with the alphabet soup guys.

What you can't do is take a receiver that started life as a rifle and turn it into a pistol.

That would be classified as an AOW (Any Other Weapon) and subject to the NFA.

But, if it starts as a pistol, and is never configured with both a butt stock and a barrel shorter than 16" at the same time, you're golden.

There are a couple of other random things to keep in mind with AR pistols.

1) You gotta have a buffer tube of one sort or another so that the bolt carrier has someplace to go when the action cycles. Ergo it is definitely NOT illegal to have a pistol AR with a buffer tube attached, you just can't use the type with mounting provisions for a carbine or rifle stock.

2) No vertical foregrips on pistols, or it goes into NFA territory again. No idea why, but that's the way it works.

3) The Magpul angled grip thing is NOT considered a vertical foregrip (Just in case you want something more to grab onto than just the plastic forearm).

4) ATF has repeatedly and publicly stated that the Sig AR pistol arm brace thing is NOT a stock and will not make your AR pistol into an SBR, even if you shoulder it and use the brace like a stock.

Still can't have a vertical foregrip though. lol


I haven't had time to check, but didn't Rock River used to make an AR with a side folder stock? The buffer-spring ran along the top like a HK91. If memory serves me, it was a piston operated system as well. A more complex operating system, to be sure, but it would eliminate the rear facing buffer-tube.

Whitehall, NY

john jay


i don't know.

para ordnance tried something along that line, but, it was short lived, and a lot of their production got picked up by the various "surplus" type dealers.

i don't know what rock river may have done.


john jay

wide machinist:

i am not competent to speak for the a.t.f., and do not pretend to be.

probably about the only prudent way to deal with them, is to contact them, and simply ask.

you know how badly we all want to be law abiding citizens.

that being said.--

my understanding about the matter is that when a lower receiver is marked as a pistol or rifle, then it retains that characterization, and is not to be changed in configuration or outfitting.

once a rifle, for instance, always a rifle, and subject to the minimum barrel requirements. this can be massaged a little bit, by getting a firearm licensed as a "short barreled rifle," but, again, a.t.f. should be contacted on how that is to be done.

my understanding is, that once a lower is a "pistol," a pistol it shall remain. this is muddied a little bit, as i am given to understand the whole thing, that a pistol may have any length barrel that one puts on it.

no stocks are to be added to pistols. to add a stock to a pistol is to make it a rifle, and this is not to be done.

this gets muddled in one respect. for those who may suffer some disability, a "brace" is allowed to be used by pistol shooters in order to allow them to manipulate and handle the weapon. and, oddly enough, the "brace" ends up looking a whole lot like a stock, and for my eyes, viewing the illustrations in the articles that i have read, is sorta indistinguishable from a stock.

the labyrinth of logic and semantics laid down by federal agencies has to be encountered to be believed: and, whether it makes any sense to us when trying to decipher them, is not a burden borne by a federal agency.

remember, too, that the federal agency has the last word in interpreting its own regulations, and what you think about the matter is not binding on them. what they think about the matter is binding on you. period.

i don't practice law any more.

i don't dispense legal advice. i don't even pretend to. anything i say in the confines of these pages is not to be taken as legal advice.

if you want legal advice, hire a lawyer. if you want to know what the a.t.f. thinks about a particular issue, or something you would like to do, contact the a.t.f., ask for an opinion, and ask for a formal letter of advice to protect yourself in further dealings with them and/or law enforcement.

it is, after all, your tookus which is on the line.

john jay

john jay

dear readers:

please read my comment above.

meaning no disrespect to wide machinist, i would suggest that rather than rely on what someone says as a comment to a blog, no matter how knowledgeable that person is or may appear to be, (and that includes me, btw), that you contact a.t.f. and/or hire a lawyer for advice in such matters, rather than rely upon opinions voiced in pages like this.

simple prudence demands that you do so.

again, it is, after all is said and done, your tookus which is on the line.

john jay


Yeah, by all means, do your own research.

The reason I know what I laid out above is because I've done said research using ATF's own rulings and material that they publish just for such.

I've got an 07 FFL, so I have to wade through the in's and out's of this crap pretty regular like, and the guys at ATF are usually pretty helpful in this regard.

To be honest, every single person I've ever interacted with at ATF has been nothing but helpful and pleasant, save for a single guy on a Friday afternoon who gave nothing but terse and commanding answers to my questions (which I took to mean that he had a date or a bass boat or something that I was keeping him from).

All my face to face interactions have been with very nice women who went to great lengths to make sure I understood how things were supposed to work, etc.

It's unfortunate that the shooters and the top level political people are the ones who end up being the "public" face of ATF, because the front line wonk type folks who actually do most of the work would actually make a much better impression on people (in my experience anyway).

Having the wonks in charge would probably result in fewer shootings and lost/smuggled firearms too.

If anybody has any questions about the NFA and/or building their own firearms, I suggest you cruise over to ATF's website and download their NFA handbook. It will outline what is regulated by the NFA and why (what characteristics matter, not the reasoning on how they chose them, that part will probably never make sense).

It's all there and free for the taking for anyone who wants to learn.

Use a proxy service if you're afraid of them sniffing your IP address, (though I'd say that a record of you trying to find out what the law says so that you can follow it shows good faith on your part more than malice, but privacy is a personal thing, so take whatever precautions you desire, but don't skip the info).

john jay

wide machinist:

a very interesting missive, and full of sage observations.

i endorse your view of contacting a.t.f. a good personal relationship can never hurt ... it may not help in every instance, but, it can never hurt.

remember something about the federal government, its minions and its authority.

case law observes that the "advice" or opinion given by an employee, unless that person is sufficiently high up in the scheme of things to have actual speaking/writing authority to bind an agency, does not legally bind an agency to a legal position.

in other words, and plainly spoken, what an employee at the counter or over the phone says to you may not be very good advice, and may not bind the government to that representation.

proceed at your peril, in other words.

as for me, once something is marked as a pistol, it stays a pistol. i may not understand things as fully as you. but, i am not going to put myself in the position of finding out who is wrong and who is right in a courtroom.

i've been in too many of them. and, seen too many federal judges, do just about what they felt like.

i may take the longer path, but, i am not walking over the spindly bridge with the large billy goat underneath it.

thank you for your read. thank you for your comments. they are quite interesting.

and, please, do come back often, and comment often.

in a day or too, i will discuss the cartridge that i am going to put in my little ar-15 pistol. you may find it interesting.

john jay

john jay


"in a day or two ... ."

sheesh. if i had half a brain i'd be dangerous.


You are indeed correct about the once a pistol always a pistol thing being the safe bet.

Plus, it's just one more reason to build a whole new gun if you find yourself needing/wanting a rifle length weapon down the line.

"Oh no hon, I HAVE to build another one. That lower is only for pistols." HA!

Opinions from ATF are not binding unless issued in writing on agency letterhead.

Those have stood up in court thus far though.

Just read your last post about the cartridge for the pistol.

I like how you think, old timer. lol

I've been mulling an AR variant chambered in 357 Whelen or maybe 338 Federal. But then I think to myself, "Something in a 458 bore would be just damned near a straight walled case if you start with a 308 or 3006", so I don't know what I'm gonna do.

Gotta finish this 45Auto carbine I'm working on first.

john jay

wide machinist:

have fun.

i always like the two day lull between projects. it's so peaceful, not having anything to do.


good luck. and, i hope that everything ends up working just as contemplated.

john jay

p.s. i think the .308 or .30-06 ends up being straight walled w/ a .452" slug, but, just a bit small for the .458" bore.

the .45 acp has the same case head as the .308 and/or the .30-06 . but, i think that silly .006" makes a difference, and that the rifle cases are just a little shy on the .458.

but, keep all posted on how it goes. when you are done, let me know, and we can "publicize" it with my readership in the 10's. laughing.


OK, I found what I was looking for -


...and a review


john jay


way cool.

been away for a while. projects. getting another computer ready to go, as my old wheezer won't do windows 7 or 8, and xp is now unsupported.

not entirely successful in that endeavor, but, will persevere and prevail. eventually.

got a new rifle to sort out. it cost a couple old guns and a bit of cash, but i acquired a dpms gen ii in .308. probably gonna rebarrel it to "jj's brit," once i get it sorted out. got the ap-4, and the only thing i don't like on it is the pinned front sight. it will be gone, shortly.

don't worry, i have not forgotten my pistol project. got a .375 sizer button and a .375 button for case trimming. gonna start fabricating cases and making dummy cartridges, for cartridge drawings and figuring case capacity and the like for quick load, to get loading parameters.

will write on that next.

then a "master" dummy cartridge will be made, and function as the go & no gauges. pretty straight forward, actually, if not a little frightening to the anal types who fear "error."

i figure, when it comes to "one-off" home projects, what's the difference between the way i do things and "tolerances." to my mind, there is none.

which is why i am not a master machinist. and, which is why master machinists don't make stuff like mine.

you can figure out the relative virtues of the two approaches. say what you will, i will remind you that john moses browning never made a blue print his whole entire gunning making life. just guns.


Sevrin Dyer

Can you design one with the Ares SCR style?

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