It's going right to the Courts and it's going to get ripped to shreds is my guess.
The seizure provision clearly violates due process, so that's why the R's went along w it- cover their ass, let the SCOTUS or, more likely, a lower Court, strike it down.
You simply are going to have to, at some point, have a standardized competenc/ mental health test at 18, and that will be the measuring stick for gun ownership.
Until we fund a way to qualify YOUTH mental health, there will never be a reduction in violent crime, with guns, knives, fists, cars or social stalking, etc.
The issue is mental fitness, that's needs to be measured somehow, that's the solution.