Crimes (including negligence) are not insurable. Accidents are few and far between. Guns are less dangerous than other items.
>>Guns are less dangerous than other items.<<
Ya mean like doctors, hospitals and Progressives?
Always a good idea to check. As Sacajaweau correctly states, criminality is never covered. I've checked this issue periodically, as I do for all sorts of possessions, and have been assured that as long as my actions are within the law, of course I'm covered, including my umbrella. But you should check, companies can exclude anything.
But the intent here it burdening gun owners, which insurance companies won't object to if it means revenue. So I'd suggest the solution would be either legislation requiring some level of liability insurance for anyone residing in the US, including illegals, or preferably legislation banning insurance companies from deleting firearms from coverage.