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If Miller was decided today, the whole GCA and NFA would be tossed. At the time, there were few automatics, and they were nearly all crew served machine guns (Tommy gun would be one notable exception, but not really a "standard issue weapon"). There were few SBRs (Again, tommy gun), and I cannot think of a single short barrel shotgun.

Now, the standard issue is a short barrel full auto, suppressors are still mostly for Special Forces, so it would be a stretch for them to be considered to be "in common use" in the armed forces, but the Benelli M4 and mossberg shotguns issued are about equally 14.5" and 18" barrels with some 20" out there.