Please read the whole article on how it will affect all weapons (esp. AR/AK Pistols):

"Under ATF’s new interpretation of the handgun definition, millions of AR-15 style pistols could be considered “too large, or too heavy” to fall within ATF’s new interpretation, thereby making them unregistered NFA weapons, and subjecting manufacturers and gun owners to criminal prosecution. Given the private nature of ATF’s classification rulings, and the subjective nature of the analysis, it is extremely difficult to know for sure whether specific firearms fall within the new interpretation. This appears to be part of a continuing trend at ATF to apply firearms statutes in a more restrictive manner without informing the public—a trend that appears unaffected by the IFR. In this uncertain regulatory environment, importers and manufacturers should consult counsel before making significant purchasing, importing, or manufacturing decisions for firearms that could be implicated by ATF’s heretofore unknown and undisclosed analysis."