PeppermillRenoHe has an excellent point even though his particular view is slightly extreme.
People who had sped ass upbringings and did messed up shit as kids are who guns need to be kept away from and those are the easy people to identify and target. Adam Lanza could have been prevented the pilot who crashed that plane in France on the other hand isn't preventable.
I really didn't feel like getting into a gun control debate for the 100th time, but okay I'll bite..
Putting prospective gun buyers though behavioral screenings would only catch an small portion of people who could potentially be dangerous with a gun. Most criminals don't use legal methods of obtaining a gun anyways, and it's my option any extreme option such as his isn't a viable one. Let's say someone gets denied buying a gun after a behavioral screening. Chances are they'll find another method to obtain a firearm. Let's also talk about costs associated with behavioral health screenings for firearms buyers. Who's going to pay for that?
Do we need to start behaviorally screening people who want to buy swords, knifes, or whatever because there's a possibility one out of a extremely large number of people may decide to go stab someone? I agree with you saying those people who may be at a heightened risk of committing a firearms related crime may need additional screening, but his previous post about adopting that process across the board was extremely compulsive and poorly thought out.