The vast numbers of gunowners own semi-automatic "assalt" weapons. They are the most popular semi-automatic rifles sold in America. That means, the red-flaggers who hate those weapons will turn in the largest percent of the gun owners. I am posting this image, again, to show the potential damage that red-flaggers can do:
“America’s Rifle,” the AR-15, of which more than 18 million are in circulation, is typically chambered in this common caliber: 5.56 NATO/.223 Remington: