The President can immediately, without legislation, direct the ATF through the Department of Justice to review the importing of all firearms. All imported firearms must be "particularly suitable for or readily adaptable to sporting purposes” according to the Act. This provides a basis for the ATF to immediately review and ban the importing of assault rifles, and any firearms not deemed to fit "sporting purposes". A narrow definition of sporting would limit imports to hunting and traditional target firearms.
This point was mentioned by Tom Diaz in an interview with Terry Gross on Fresh Air on Dec. 20, 2012.
This can be done by executive order without waiting another day. Another day cannot pass without a definitive action by the President. This action would be the start of the longer process led by VP Biden.
Please act now.