In September 2017 Petersen was banned from Facebook during his senate campaign for giving away an AR-15 style rifle as a promotion and criticizing his Democratic opponent Claire McCaskill's positions on gun rights. The ban was lifted after Fox News and the "New York Post" reported that Facebook's COO Sheryl Sandberg had made max donations to McCaskill's campaign. The raffle drew renewed controversy in February 2018 when the school shooting in Parkland, Florida caused the "Springfield News-Leader" to investigate. KMOV in St. Louis scrutinized Petersen over his views on gun control in light of the shooting.