TexasCHLforum.com

The HPA includes a provision which nullifies any state registration requirements, but doesn't nullify any outright state silencer bans (e.g. California).

In another thread about this paper, a poster asked if that the idea with the HPA was to treat silencers like rifles, and recieved a reply in the affirmative. That thread is now closed, so I can't reply there, however I'd still like to point out that this is incorrect.

The HPA, as written, would remove silencers from being regulated by the NFA, so transfers would be cash and carry after filling out a 4473 and passing NICS, and would be legal for private sale to other state residents. However the HPA doesn't include silencers in the exemption which allows FFLs to sell rifles and shotguns to 18-20 year olds, nor does it include silencers in the exemption which allows FFLs to sell rifles and shotguns to residents of other states. A better statement would be that the HPA modifies the law to treat silencers like handguns.

It's not an official ATF whitepaper, it's just the opinions of an ATF bureaucrat. If I had to guess, I'd guess that:

1) This is an unofficial way of the author trying to get his name in the news so that he'll get offered the job of ATF director.
2) This "leak" consisted of the author emailing the document to the Washington Post.