Proposed: The owner of record is responsible for the harm done by any projectile leaving a muzzle. Those legally eligible can own any firearm they choose, but they assume all legal and financial risk for its use.
Every gun made is the responsibility of the maker. As it is sold, it is registered -- not with the government, we cannot have that -- but with the "National Firearms Association" or some such group. The 'NFA' collects a sample slug and casing (assuming that CSI stuff works in real life) for later comparisons. This forensic data is shared with law enforcement agencies. If a close match is found in a criminal investigation, the identity of the gun owner is produced, as required by court order.
The 'NFA' has a business opportunity: sell liability to responsible gun owners, new or existing. They (or competitors) can determine, though their own wisdom and statistical analysis, who they will sell insurance to and for how much. If they happen to think that Bushmasters with 100-shot magazines sold to 23-year-old's in high-crime neighborhoods are a worse risk than, say, over-and-under breech-loading shotguns sold to old duck hunters in northern Minnesota, they can set policy prices appropriately. If the maker/seller transfers the weapon to someone who does not obtain insurance, they retain liability. Makers have incentives to consider the sorts of products they wish to assume liability for, and where they go.
After the sale, the registered owner (or insurer) is deemed to be responsible for any crime or damage traced to that weapon. Period. The owners have every incentive to assure the gun is safely stored. If they choose to keep it loaded in the glove box or under the bed, that is their choice and their assumed risk. Again, if they sell it, their liability extends until it is re-registered with the NFA and insured by the new owner. If it is stolen, that is noted, but the buyer may still have some liability if they are found to have not stored the weapon appropriately, or to have not reported the loss. If a household member uses it for suicide or a crime, the owner is, at least, culpable for negligence.
There is no ban on weapons for law-abiding citizens. There is no government database of gun owners. There is a business opportunity for the 'NFA'. People have incentives to behave responsibly. There are free-market cost signals about risk and responsibility. As I understand the arguments of 2nd Amendment & free market proponents, they cannon object.
A frequent reader, infrequent comment-er, 1st time diarist. I welcome any discussion.
I am truly puzzled as to why I have not seen this idea stated before, or why it is not reasonable and attainable.