Bump stocks are currently legal under both federal law as well as Nevada firearm law. But in light of the Vegas Massacre on October 1st, many Democratic lawmakers in Washington D.C. are pushing for a nationwide ban of bump stocks.
Bump stocks are rifle accessories that take place of the gun's “standard stock,” which is the piece that rests against the shooter's shoulder. As long as the shooter holds down the trigger and places pressure on the barrel, the bullets will fly almost as quickly as an automatic firearm. During the Vegas Massacre, the shooter was able to unleash approximately 90 shots in only 10 seconds.
The rapid firing of gunshots during the Vegas Massacre sounded like an automatic weapon like a machine gun, which are banned under federal law unless it was lawfully possessed and registered prior to May 19, 1986. Instead, the shooter used several semi-automatic weapons that he modified with bump stocks, which allowed the firearms to fire faster. Bump stocks do not technically convert semi-automatic guns to automatic ones, which is explains their legal status.