For handguns or rifles? Pistols are the only guns that I know of that require a waiting period, and I didn't know that any state waved that, but I could be wrong.
I know the country-wide ban on automatics has expired for quite a long time. But to be safe, do what eindecker said. Also, I believe you can call a firearm that is 100 years and older an antique, and is legal, but don't quote me.
I think its automatic-ness would supersede its antique-ness in terms of law.
The class 3 terminology that keeps popping up sounds familiar, and earlier I said it could be invasive. By that I mean it allows the government to check up on the status and proper storage of the gun at any time. But that is situational, because it is not allowed in every state as far as I know.
If you are wondering, the only way you could legally own an automatic rifle without all the paperwork is to go back before the weapons ban and buy them all, then keep them under the grandfather clause.