Fully-Automatic firearms are banned in the US, but there is a stock called “Bump stock” that turns a semi-automatic firearm into a fully-automatic firearm and they are legal in many areas in the US.
But the US is finally taking this seriously and moving to ban the sale of these bump stocks and classify them as machine guns.
This is a video that explains what is a Bump Stock and how does it work on a Semi-automatic rifle like the AR-15
