Need a multi-pronged TOUGH approach, and it WOULD have a noticable affect.
If the perps know that the victims WILL return fire right then and there (takes arrest, trial, waiting for sentencing, possibility for plea bargaining out of the scenario) THAT ALONE would stop a lot of the “wannabees”
And tough prison conditions (or states that have the death sentence) make the professional criminals look elsewhere; the professionals do think ahead and have a strategy to their criminal activity (that’s what differentiates them as professionals) … see my Nevada/Montana evidence above.
of course nothing is going to stop the perp who’s also suicidal himself and wants to go out “in a blaze of glory”