Have you not noticed the advertisements from distilleries, encouraging people to not drink and drive? Why do you suppose they do that? People have successfully sued bars and restaurants who served alcohol to people who then drove while impaired. Distilleries are careful about how they market their product.
I have not advocated taking firearms away from people. There are people who should not have access to any weapon, let alone an assault rifle. Every day in America a Veteran voluntarily surrenders at least one weapon at a mental health facility. As the Administrative Officer of the Day (night manager) at a VA Medical Center I have locked up, in my safe, weapons surrendered to me in the past, Systems designed to keep us safe work remarkably well most of the time.
Accountability is important. People who advertise "Unleash the Fury," "Forces of Opposition Bow Down," and "Consider your Man Card Reissued," are not marketing to 'Hunters." Because they are legally immune from civil prosecution, they can appeal to peoples' aggressive tendencies in selling mechanisms for mass murder. They need to be accountable to victims of people "unleashing the fury." Allow them to be sued, like anyone else can be.