SOLVED. Adult Fictional book about a mass shooting that leads to mandatory gun buyback

[Ryan]

I read part of this book back in 2011 or so, it's about a conspiratorial plot where a patsy is blamed for a shooting at a stadium, and that is the catalyst for the government to institute a mandatory gun-buyback program and shut down all of the gun stores in America. I cannot remember the title or author, but I think the cover had the Gadsden flag, and the title might have been something related to a slogan or saying from the revolutionary era.