ATF rules a 14 inch shoe string is a machine gun:
A rubber band is a machine gun:
In fact, you can rapid fire a gun simply by how you hold it to your shoulder
So, please provide a list of all things to be banned to prevent rapid fire of any gun. Start with bellies, hips, shoulders, and fingers, because any of those can be used to do it.
The reason gun rights supporters object to the banning of a relatively useless range toy is that it is just one more meaningless, feel-good-only, ban from the left. It's that pattern of banning these that have no effect on the murder of babies in Chicago and other cities that worry us because bump stocks are just one in a long history, and longer plan going forward, of meaningless, ineffective, bans that are designed, in the end, to remove our ability to exercise our natural right to the tools of defense.