Are we talking Red Dawn "obtain the Form 4473s" type of confiscation, or "dem darn liebrals gonna take argh guns!!1!"?
The moment legally possessed and BATFE-registered Title II weapons, owned by the most law-abiding citizens this country has, are 'nicely asked' to be handed over to Uncle Sugar will be the moment civil unrest like this country has not seen in decades will begin.
The moment the first law-abiding owner gets no-knocked in the middle of the night to seize their Title II weapons will light the match that starts a fire most folks simply cannot comprehend...and it won't be limited to folks who are stamp collectors.
In the beyond highly unlikely event a circumstance as posited ever presents itself the brownshirts can have my suppressors and registered SBR lowers....cuz I might just maybe possibly have other, non-SBR registered lowers that are functionally identical to the ones in BATFE's registers.
several states are already confiscating guns and mags..... no one is doing anything.