When you get to the underlying facts, gun bans and gun control laws aren't really about protecting the citizens - their goal is to take power away from the citizens. While the right underlying the U.S. Second Amendment is a fundamental individual right, the Founding Fathers had very fresh experience with having to throw off the yoke of a tyrant. (I understand if our Loyalist neighbors to the north have a different take on what happened in the 1770s, but that's the view down here, and the principle remains regardless of your opinion of King George III.)
The left wingers today in North America are Neo-Communists of the Marx/Lenin tradition, and if they somehow gain total power and turn your or my country into a 21st Century Soviet Union, they don't want the citizens to have the ability to depose a Stalin to restore constitutional government. A rifle chambered for .50 BMG certainly wouldn't be the weapon of choice for a mass murderer (too heavy to be very portable, slow rate of fire in rounds per minute even in semiauto due to cartridge size, etc.), but it would be useful to patriots restoring constitutional government to the land against a despot's army. That is how the proposed .50 BMG ban shows their desires.
