Sensible legislation already exists. Before anyone in the U.S. can purchase any firearm, in any state, they must undergo a full background check. You cannot buy a firearm if you: Have been convicted in any court of a crime punishable by imprisonment for a term exceeding one year;

    Are under indictment for a crime punishable by imprisonment for a term exceeding one year;
    Are a fugitive from justice;
    Are an unlawful user of or addicted to any controlled substance;
    Have been adjudicated as a mental defective or committed to a mental institution;
    Are illegally or unlawfully in the United States;
    Have been discharged from the Armed Forces under dishonorable conditions;
    Having been a citizen of the United States, has renounced U.S. citizenship;
    Are subject to a court order that restrains the person from harassing, stalking, or threatening an intimate partner or child of such intimate partner;
    Have been convicted in any court of a misdemeanor crime of domestic violence.

I repeat: This is a national requirement, not state. Most states impose their own, additional conditions; in my case, simply to purchase ammunition for hunting, I had to pass a secondary background check and pass two courses, one involving hunting and one on gun safety.

When it comes to handguns, almost every state has requirements for carrying pistols, which often include requirements for training, supervised range time, and, yes, more background checks.

When people start wringing their hands about needing more legislation to keep guns out of the hands of the wrong people, I immediately know that they're just spouting bullshit and don't have a clue what they are talking about.

We already have sensible legislation. What we don't fucking have is adequate care for our mentally ill. We also don't have a society that has any resemblance of economic parity, and one that demonizes 50% of its population for being the wrong gender.

Gun control is just a shibboleth. The real key to dealing with gun violence is not the guns, but the underlying mechanisms leading to their misuse.