I don’t think your assertion about locality of gun crime and gun laws in the US is consistent with the data. (Not trying to make an assertion as to whether such laws are effective here)

Sort state level data by gun murder rate, it’s not so clear cut: https://en.m.wikipedia.org/wiki/Gun_violence_in_the_United_S...

States like Louisiana and South Carolina have the highest rates. Maryland is a state with high rates and also more stringent gun laws, but New York and California are pretty far down the list