I do not need a reason beyond fully understanding what the 2nd Amendment is, and is FOR.
However, sure, to answer the less important part of the question: Banning bumpfire stocks would be quite unlikely to be as straightforward as banning items sold as bumpfire stocks. The version of a bill to this effect published at the moment says it bans, "a trigger crank, a bump-fire device, or any part, combination of parts, component, device, attachment, or accessory that is designed OR FUNCTIONS to accelerate the rate of fire of a semiautomatic rifle..."
Think hard about that for a moment. Just how far would such a ban reach into all of our gun safes? Good heavens. A huge number of things could be swept up into that pile. Binary triggers, "Hiperfire" triggers, any trigger that is lighter than ... well, nobody knows how light because ANY semi-automatic trigger can be bump-fired, all sorts of springs, stocks, parts, etc. And even unrelated stuff.
And, to get really into the meat of it, look at the ATF letter on PGO shotguns that have barrels less than 18" long but are still over 26" so are not NFA Firearms. The ATF has set precedent there by saying that if you do conceal one, like by putting it under your long coat, then you've disproved the assumption that this is not a concealable firearm, and that kicks it into the category of "AOWs" under Title II, so you're now a felon.
In other words, what you DO with it matters.
You don't have a device designed to accelerate the fire of your semi-auto rifle? Well, fine, but somebody just saw your "accidentally" double a few shots off a bench testing out the trigger on your AR. That's bump firing. And you just displayed a rifle that accelerated the rate of fire EXACTLY as a bump-fire stock would do. Whoops.
You hear this as a simple thing. You see this as putting the folks at SlideFire stocks to the guillotine, c'est la vie, and all will be well. But that's not how laws are written nor how they are enforced.
