I think AR's will be targeted by the Democrats much more aggressively than your standard semi-automatic pistol. Not that any of this is true, but it's easier for an idiot politician to convince the typical voter than "weapons of war like AR15's" shouldn't be in the hands of the average citizen, while that same typical voter would more likely understand that a simple handgun for self defense would seem "more viable".
Having a few stripped lowers tucked away in the safe is never a bad idea.
That said, if you asked me, I would concentrate more on establishing a nice cache of ammunition versus spending your dollars on a bunch of currently low-priced pistols.