Policies can work in one country and not another.
We have the strictest gun controls in the world. So strict that our medal-winning olympic pistol team can only practice with air pistols in the UK and have to go overseas to practice with the real thing. Americans look at us and think it is overly draconian. They don't seem to realise that people do own shotguns here and that there are still rifle clubs and cadets rifle training.
I think that our gun controls have been a success, but I can also see that they probably wouldn't work in a country as vast as the United States, with their history and antipathy towards government restrictions. The sadness is that the United States seem unable to have a constructive conversation that reaches a middle ground in which the gun lobby feel they retain the freedoms they need, while mentally ill school shooters find it harder to get hold of assault rifles designed to kill people. My view is that Charlie Kirk was all about facilitating a culture in which debates like that could happen.
As it happen, given the professionalism of this assassination, it is possible that gun controls would have protected him yesterday. They tend to protect against the mentally ill, but unsophisticated potential murderer.