This week, Karen Mallard recorded herself cutting the barrel of an AR15 and posted the video on Facebook. By doing so she violated the federal National Firearms Act of 1934 and committed a felony, publicly. 

26 USC 5861 D. Sawed-off rifle with a barrel length of less than 16" or overall length less than 26"; Punishable by up to 5 or 10 years imprisonment, depending upon specific violation.