Miller originally tried to plead GUILTY to NFA violations! The judge didn't let him.
Here's some info about the Judge who found "for" the Second Amendment in the original trial.... he was a rabid gun-banner:
D. JUDGE RAGON
The newspapers assumed Miller was a “test case of the National
Firearms Act.” They were probably right. The government
needed a Supreme Court precedent holding that federal gun control
does not violate the Second Amendment. Ragon teed up the case.
Ragon did not really think the NFA violated the Second
Amendment, and probably colluded with the government to create
the ideal test case. His opinion is peculiar on its face, begging for an
appeal. A memorandum disposition is appropriate when deciding a
routine case, but not when holding a law facially unconstitutional.
And Ragon was the first judge to hold that a federal law violates the
Second Amendment, even disagreeing with a Florida district court
that had dismissed a Second Amendment challenge to the NFA.110
Before he became a judge, Ragon represented the Fifth District
of Arkansas in Congress from 1923 to 1933.111 As a congressman,
he was a vocal advocate of federal gun control. In 1924, Ragon
introduced an unsuccessful bill prohibiting the importation of guns
in violation of state law,112 and vigorously supported another bill
prohibiting the mailing of most pistols, which eventually passed in
1927.113
Basically, Ragon wanted to prohibit firearms used by
criminals, including pistols.114 “I want to say that I am unequivocally
opposed to pistols in any connection whatever. If you want
something in the home for defense, there is the shotgun and the
rifle, but a pistol is primarily for the purpose of killing somebody.”115
And he specifically dismissed Second Amendment objections
to federal gun control. “I cannot see that violence to the Constitution
which my friend from Texas sees in this bill.”116 If Arkansas
could prohibit pistols, so could the United States.117
Read this article:
http://uknowledge.uky.edu/cgi/viewcontent.cgi?article=1263&context=law_facpubUS v. Miller was a deliberate and successful attempt to screw the Second Amendment.