This is achieved by allowing the entire weapon to slide back and forth rapidly within the stock, causing the trigger to reset and fire again with each bump. Here are key points about bump stocks ...

When the trigger is pulled the bump stock uses the firearm's kickback to slide the weapon back and forth quickly, allowing it ...

to increase the rate of fire. "While the bump stock might be a self-acting mechanism to allow the rifle to slide back," he said, "it is not a self-acting mechanism to maintain the forward pressure.