Sure, if you want to permanently extend the barrel length to 16", it is now a rifle and you can use any stock you want plus even a fore grip. Its my understanding that a pistol can become a rifle but a rifle cannot become a pistol. It does not have to be a rifled barrel extension which is mechanically impossible, or shall I say something which is simply not done. All manner of devices have been used to extend to the legal barrel length, such as flash hiders, faux silencers, extended muzzle brakes, etc. The approved attaching procedure is to pin after installation and to weld the pin into place.
I don't want to do this - I want to be able to have my rifle-caliber pistols and use them. However if this goofy ban stands, I have some ideas for keeping them legal.
The AR pistol in particular is interesting because it must have a lower receiver extension (buffer tube) in order to be functional, so that cannot be included in banned devices, although it cannot be the type that has the mount for a stock/'brace' on it. Seems like a plain 'pistol' buffer tube with a foam rubber cover on it for use as a cheek rest for aimed fire would be okay based on what I have read in the text of the ruling. But, you must keep in mind that most of the people writing this crap don't know jack about guns in the first place.
The bump stock ban's wording conflicting with NFA1934 is something I wrote about pre-Covid, and I'll give you the gist of it; NFA1934 is very clear on what constitutes a 'machine gun', and in a nutshell, it must fire more than once for each manipulation of the trigger. The bump stock does not cause doubling or other uncontrolled multiple firing - the trigger re-sets after every shot and must be pulled again for the next shot - the bump stock is just a toy that makes this easier to do. Shooters have been 'bump-firing' with just their trigger finger since self-loading rifles were invented over a hundred years ago. Nothing is new, and none of them became 'machine guns' when bump-fired.
Okay, so when they wrote this ruling up, they justified calling it a 'machine gun' because it caused multiple shots to be fired without separate trigger pulls. Since this is obviously an impossibility and hence a false statement, now the entire portion of NFA1934 relating to machine guns is rendered obsolete since the new rule has a different and nonsensical definition for 'machine gun' which could never stand up to a simple mechanical demonstration.
You could say that the way to ban the bump stock without affecting NFA1934 would be to simply ban any kind of device that aids in rapid firing. Of course, that would be extremely weak and would amount to simply banning rapid fire beyond that which can be accomplished by hand and using no devices, a rather inane exercise and one sure to fail in any court.
This is why they had to pollute NFA1934 with the ridiculous notion that a bump-firing device is a machine gun, so that those who didn't know any different would support it.
So, how long can this stupidity hope to survive scrutiny by anyone with two brain cells to rub together? Apparently, by the recent court decision against it, that time is running out.
The 'pistol brace' deal is a different matter. A long-gun 'pistol' with any of the popular 'braces' on it, has the exact form, fit and function of an SBR. Anyone being honest has to have seen that coming from day one. So, even though I hate this, it is obvious to me that it would be exceptionally easy to prove this in court, and so the 'pistol brace' is a thing of the past - it definitely is on my pistols. Look, they don't allow stocks on handguns either, right? So can you imagine fitting a 'brace' to your 1911 or any other handgun that looks like a stock and which you put to your shoulder when firing? Its not going to be allowed! Sure, it would be great to vacate these sections of NFA1934 so SBRs were everyday guns, but until that happens, we are going to have to live with it - but we shouldn't have to live with patently ridiculous rulings like the bump-stock ban.
