http://reason.com/blog/2017/10/11/your-bi-partisan-bump-stock-ban-has-arri
I own several guns. Most of them have been modified with aftermarket parts to make them more accurate.
Custom triggers, muzzle brakes, heavier recoil springs, polished slide rails, modified magazines to make feeding smoother and more reliable.
All of which, incidentally, allow me to fire more rapidly, by anywhere from 5-10%.
Under the so-called Bump Stock Ban, all of these modifications would become illegal.
Retroactively.
In order to avoid criminal charges and prison time, loss of my property (including my house and car) through asset forfeiture, etc., I will have to restore these firearms to factory original condition and destroy the parts.
Not happening.
Anything that you do to make a firearm more accurate will also make it faster to fire.
I'm going to prison, because I'm a target shooter who wants his firearms to be as accurate as possible.

And the ban is stupid. You can bump fire without any extra equipment or modifications at all. Not even a belt loop.