I don’t think that’s an insurance issue, that is liability... allowing manufacturers, merchants and gun owners to be sued if a gun they made or owned was used in a way that caused injury or death to another person. The republicans passed a law a few years back preventing manufacture liability lawsuits. Manufacturer and distributer liability could be a major deterrent to the production and sale of weapons like the AR15 if they were held responsible every time one was used to kill some one, let alone 34 people.
This type of insurance is about liability.