comment: >
  
  Because of the tommy gun, or Thompson aub machine gun. All this legislation dates back to 1934 when the police were wildly outgunned by gangsters. Automatic rifles and sawn off shotguns and short barreled rifles were their tools of choice so they were regulated under the NFA. SBR's aren't illegal, you just need to register them and pay a special tax. 
  This is an absolute cluster of a set of laws and regulations because modern platforms allow the various bits to be swapped fairly easily, so the rules make little sense in the real world.
context: As a European why exactly are short barrel rifels such a threat to society? Compared to either pistols or long barrel rifels. >
  
  The idea is that they’re easier to conceal. Same reason you can buy a rifle in 15 min (in some states) but a pistol still requires a longer background check. Useless law either way IMO >
  
  OK but still why outlaw them so drasticly compared to the easy to concear handguns.