Let’s start by repealing the NFA of ‘34.
That’d be a good start, for sure.
The NFA was pretty much re-written in '68, and that is the law that would need to be repealed. I say repeal them all.
The only problem would be that owners of Class III firearms would see the values drop precipitously. A transferable M-16 from before '86 is currently worth about $20K. If these acts are repealed it would probably drop to about $2K in value, depending what the manufacturers would charge for a new one.