if you own a fucking gun you should be held responsible for what harm it does... criminally and financially
So if someone steals your car and then kills someone (vehicular homicide) the owner of the car is responsible?
If your home is invaded by criminals and they steal your guns is the homeowner responsible for the perp killing someone with the stolen gun?
If your kids are playing baseball at the park and an angry bully grabs a bat and whacks another kid in the head is the owner of the bat responsible?
Is the local co-op responsible if someone purchased 2 tons of fertilizer and creates a bomb that is used to kill others?
Read up on what insurance companies will cover and won't. Gun coverage as you suggest is a non-starter. Unless you want to start a new business model and try it out for yourself. Good luck with that.
How many gang members or other thugs are going to line up to purchase insurance for their guns? Hmmm.....ZERO.
How many people drive cars without insurance? How many die from those drivers? Happens all the time.