I wonder if it would be legal to remove the arm brace.  Or cut the extensions off that overlap the arm.  I find those useless and with the pistol illegal, according to the ATF, if shouldered, the effectiveness of the brace is kind of pointless.  Too difficult to get in and out of that brace. But if cut off it would make  it a bit easier.  Just grab the pistol somewhat the same way and pull the strap.  Without those flaps, it's much easier to get into it.

I know modifying the brace to shoulder is definitely illegal, at this time, without going through the whole SBR hoops.  But cutting the flaps makes it less likely to be shouldered and I'd thing that would be ok.  But you never know about the ATF interpretations, on a gun they are having 2nd thoughts about.

Modifying the brace in any way would require you go through the approval process from scratch to determine its legality. Replacing the current buffer tube with a standard pistol buffer tube with no brace would have no legal issues.

It's not illegal to have a pistol with a brace. So far nobody at the ATF has taken any enforcement action against anyone for shouldering a pistol with a brace.

The director of the ATF has been forced to resign over the recent attempt to ban M855 ammunition (https://www.atf.gov/content/atf-announces-b-todd-jones-depart), so I don't think the ATF is going to be too slap-happy enforcing stupid bans for a while, at least until public scrutiny dies down a bit. Especially given the opinion letter's creative redefinition of "redesign" that is unlikely to hold up in court.

IANAL, YMMV, etc...

I guess I understand the point about modifying the brace, because the ATF would have to determine that whatever mod was done, wasn't for the purpose of making it shoulder able, or violating some other ATF rule.   But I don't understand the 2nd sentence.  If one replaced the  buffer tube, it could just as well be for the purpose of making it easier to shoulder.  So I don't see what rule would allow one without the other.  Why couldn't one simply remove the existing brace, without changing buffer tube?  

I don't see why the buffer tube needs to be changed.  What operating rule would require that?  Since shoulder stocks (per se) are forbidden, removing the item that seems close to a shoulder stock wouldn't be afoul of any law that I know of.  It would actually make the firearm less shoulderable.  We add compensators without any issues.  Of course the ATF might look at them, but we don't need approval before adding them.  Only after the ATF has made some determination, do some things become illegal.  There certainly isn't any rule about making an existing pistol more compact.

The ATF rules on the design of firearms.  The ATF might get after an individual ONLY if they have created an illegal weapon.  Or to put it another way, individuals modifying pistols don't need ATF approval beforehand, unless they believe they are creating an NFA firearm.   For instance, say the pistol had no brace at all, and was approved.  If an individual added one, the ATF might say, "hey, you just added a shoulder stock and that is illegal", according to NFA.

What would be "illegal" about a pistol in that configuration?  I doubt the ATF would have any argument and since we don't routinely run to the ATF for modifications unless there is good belief we are creating someting illegal, if no one can say what might be "illegal" in that configuration, I don't see any issue.

You could, but you might not be able to get the brace off without ruining it. Changing the buffer tube would probably be easier. You'd have to buy a new tube, but you could sell the tube with the brace on it and recoup your money.

From the pics I have seen, without the brace it looks like only a friction fit.  And it does rotate fairly easily.  I suspect it's just a tight friction fit.  I'm only interested in compactness at this point.  The brace is really big. ;)

Correct, the brace is friction fit.   You can slide it off if you wish without any damage to the buffer tube..

Is any modification to any existing stock illegal ?

If you were to cut the bottom off an M4 stock (assuming it fit a pistol buffer) to make a cheek rest, would you have to submit it to ATF for approval ?

I wonder how ATF differentiates this from a Thordsen buffer tube cover kit ?

Once a stock, always a stock, no matter how much left ?

That's been dun befoe. No go.

On a rifle, no.  But this is a pistol.  There is "technically" no stock.  If you make it a stock, it becomes illegal.  At least that's the way the ATF sees it.  You cannot add a stock to a pistol, without filing the NFA paperwork.



I'm not sure how you could call it a cheek rest.  That goes on a stock, for shouldering.  And you can't have a stock on a pistol.

I have a hunch it works like this, after thinking about it for a while.  

Any firearm you buy over the counter that is legal without NFA paperwork, can be worked on ANY WAY YOU LIKE, provided you don't turn it into an NFA firearm.  For instance, you can't cut a rifle barrel shorter than 16.5", without making it a SBR and doing the NFA paperwork first.  You can't add a stock to a pistol.  Any modification to a stock, for instance, on a pistol, may not be for the conversion to a stock because that would turn it into a SBR.  

So, removing the brace should be ok, because what's left isn't an NFA firearm.  It would be really no different from removing grips from a handgun.  But filling the brace with material, to make it work better as a stock, could most likely run afoul of the ATF, as it would be converting a brace to a stock.

I'm not exactly sure how they got to add the forearm on the pistol and it's clearly made for support (i.e. firing with 2 hands).  And what about adding a vertical grip.  Seems that would be problematic.  These pistols need to come with an ATF law library. :)

This whole conversation is ridiculous.