It seems to me that laws regulating "sound suppressors" only cover objects, devices or firearm parts that are attached to, or form part of the barrel/bore assembly. Ammo, is neither "attached" to, nor does it form an integral part of a firearm.. It is something "cycled" trough an action and expelled from the firearm. I don't think current legislation acknowledges this type of ammo to even exist, or is it mentioned? ON the other hand the wording of the law probalby allows it to pretty much englobe anything a grouchy AFT agent wants it to...
I think this would make a cool car gun, being that you can fire from inside with out going deaf. Any ideas on energy/muzzle velocity?