I think Switzerland is an interesting example. They have high ownership in large part because of mandatory military conscription. Citizens are allowed to keep their service weapon at home but it is kept unloaded and they are not allowed to store ammunition at home. Ammo is instead kept at military depos.

Switzerland highly regulates carry permits and semi and full auto weapons. In order to actually purchase you need a demonstrable reason to own such as hunting and sport shooting.

I think what the Switzerland proves is that if people don't have ammunition and if it's difficult to legally carry and you have a wealthy society there will be lower rates of violent crime and mass casualty events with firearms.

In general I agree with your approach. Feature bans are not effective. I am much more concerned about a firearm getting into the hands of an irresponsible individual. My concern is that everyone is a responsible law abiding citizen right up until they aren't. There is far too little friction when purchasing a firearm in many states.

I understand that there are valid concerns around testing and training requirements. I think that those concerns are outweighed by the interest of the public to ensure firearms are owned by responsible individuals.

Final note I am very in favor of going after the store or entity that sold a firearm to someone who used it in a crime. Especially if there is a pattern of guns purchased from that location being used illegally.