Guns are now killing as many people as cars in the U.S.

[NickB79]

51. Except that's not how liability insurance works

Liability insurance is specifically exempt from paying out when a criminal act is performed. That's why insurance won't pay out if you, say, burn down your house for the insurance money.

https://en.wikipedia.org/wiki/Liability_insurance#Insurable_risks

Generally, liability insurance covers only the risk of being sued for negligence or strict liability torts, but not any tort or crime with a higher level of mens rea. This is usually mandated by the policy language itself or case law or statutes in the jurisdiction where the insured resides or does business.

In other words, liability insurance does not protect against liability resulting from crimes or intentional torts committed by the insured. This is intended to prevent criminals, particularly organized crime, from obtaining liability insurance to cover the costs of defending themselves in criminal actions brought by the state or civil actions brought by their victims. A contrary rule would encourage the commission of crime, and allow insurance companies to indirectly profit from it, by allowing criminals to insure themselves from adverse consequences of their own actions.

It should be noted that crime is not uninsurable per se. In contrast to liability insurance, it is possible to obtain loss insurance to compensate one's losses as the victim of a crime.

Mandated liability insurance on firearms would have no impact on the harm done by the illegal use of firearms in the commission of a crime, which would compromise the vast majority of the $250 billion dollar amount you stated. And that's even assuming someone who's apt to commit a violent crime with a firearm would bother to get liability insurance in the first place. If someone were caught in the crossfire of two criminals exchanging gunfire, as in the example you gave, and the shooters by some miracle had insurance, liability insurance wouldn't pay out anyway.

Liability insurance on firearms would mostly just cover acts such as accidental shootings.