To effect gun control leaders already controlling guns simply need to set an example.
Simply replace dumb offensive weapons with intelligent defensive ones.
Attackers can be disabled with sound, electrical impulse (a laser to the eyeball goes a long way), gas, anything but hot lead is relative progress.
A huge industry is waiting once this direction is set and it’s a rare example where a leader can set something so important in motion. A police force equipped with such weapons would not only save lives it would restore confidence, replacing fear with respect.
Like any old technology guns will inevitably become obsolete, outmaneuvered by weapons that save lives. Even in the worst case the result is a technological arms race, with one side committed to protection - an outcome far better than shoot outs and more deaths every day, most often at the hands of those intending to uphold a form of peace.