Don't know if you guys have seen this, but Franklin Armory has thought way outside the box in getting a long gun with a 11 1/2 inch barrel to not be a SBR (Short Barreled Rifle) and not need a tax stamp.
Most of us have seen or shot AR pistols with arm braces that get you close to the advantages of a SBR'd AR rifle. Kinda of a workaround of Federal laws regarding rifles.
Now these guys have figured out that in order to be a rifle you have to have rifling by definition. If you are a smooth-bore you fall into some of the shotgun restrictions.
How do you get a long gun, with a real stock, barrel under 16 inches and not be in NFA territory? Well it seems you put lands and groves in your barrel so it's not a smooth-bore, but you don't put a twist on them so it's not technically rifling. Yes, straight rifling is not legally rifling. Then the barrel length rules don't apply and you sell it for $2K.
http://www.recoilweb.com/franklin-armorys-reformation-revealed-133042.htmlNot sure if it will be successful, but hey, they trying wild stuff to get around the laws these days.
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