Sorry you have a problem with deductions. 
All the rest of the world is a pretty good "experiment." The US is unique to have such gun-violence problems.  
Until a time such as we all have danger profiles that have been determined by government from mining our every communication (we're halfway there; sorry, no data on that just common sense) and from examining all our lifelong medical information, and that cumulative information is put toward deciding if we can own firearms--- I'd say we're just going to have to try a lot of different approaches. All firearms must be registered. Want to own a gun? You must pass a test of sorts (NRA surely would help with that, right?). 
Or, let's just continue down the road of mass shootings and homicides, occasionally shaking our heads that nothing can be done because, after all, the government is just waiting for guns to be outlawed so they can put us all in chains.
Righto!