The opening brief in Hollis v. Lynch machine gun case (formerly Hollis v. Holder) has been filed and is available to read at http://media.wix.com/ugd/c601ae_58e8e369989343ccbdbafdc9d2b5537a.pdf.
The brief does an excellent job at discussing the reasons why the Hughes Amendment should be overturned. Under the Supreme Court's decisions in Heller and McDonald, the complete ban on machine gun ownership established by the Firearm Owners' Protection Act of 1986 "cannot pass constitutional muster."
The brief also details the fallacy of the "dangerous and unusual" doctrine and how it does not apply to the "mere possession of a firearm (or other weapon)", but instead to the "manner in which that right is exercised" or "types of conduct with weapons." The origins of the term stem from old English common law that intended to preserve the right of "Gentlemen to ride armed for their Security", while prohibiting carrying weapons with "evil intent" was prohibited. one old English case cited to from 1686 clearly summarized the purpose of the rules from which the "dangerous and unusual" principle arose, stating, "[N]o wearing of arms is within the meaning of this statute, unless it be accompanied with such circumstances as are apt to terrify the people" by causing "suspicion of an intention to commit an act of violence or disturbance of the peace." When Heller stated that the traditional right to arms "was not a right to keep and carry any weapon whatsoever in any manner whatsoever and for whatever purpose", the carrying of dangerous and unusual weapons is simply a time, place and manner restriction on the carrying of protected arms, not a ban on possession.