The right to keep and to bear arms is based upon two principles: security of a free state, and a well-regulated (trained) militia (National Guard). Thus, the Constitution admits to some vetting as to military age; soundness of mind and body; and training in the proper use of the weapon of personal choice.
The more complex and powerful, the more need to demonstrate skill in target practice; in cleaning and storing the weapon; and the security against unauthorized use. The vetting should be more than the “processing” depicted in the comedy film No Time for Sergeants. Although the film’s military psychologist’s question “Do you hate your mother?” might be a good question, the generic issue of “hate” certainly is – particularly, do you hate yourself? I guess every gun shop should have a room with a couch and a chair with a trained questioner at least.
Thomas J. Zwemer