Read in isolation, Miller’s phrase “part of ordi-
nary military equipment� could mean that only those
weapons useful in warfare are protected. That would be a
startling reading of the opinion, since it would mean that
the National Firearms Act’s restrictions on machineguns
(not challenged in Miller) might be unconstitutional,
machineguns being useful in warfare in 1939. We think
that Miller’s “ordinary military equipment� language must
be read in tandem with what comes after: “[O]rdinarily
when called for [militia] service [able-bodied] men were
expected to appear bearing arms supplied by themselves
and of the kind in common use at the time.�
Pg. 52
Here's where I can see something happening, where automatic weapons could be challenged, Miller happened in 1939, automatic weapons were in common use anywhere around the world, in any militia or in any standing army. In WWII, we used the m1 garand as our main weapon in common use for our army, automatic weapons were not nearly as plentiful so they can be argued they were not in common use. Now we use an M16 (variants) that is an automatic weapon, nearly every police force, and military force issues them out to every one of their members, that would be in common use.
See my logic? I can see this wording being very helpful, and am excited to see what might happen!