Alec Baldwin has asked a judge in New Mexico to dismiss a five-year firearm sentencing enhancement in the charges against him, saying it is unconstitutionally based on a law passed after the shooting on the set of the film “Rust.” The Friday court filing from the actor’s attorneys said prosecutors committed a basic legal error by charging him under the statute. Prosecutors did not immediately respond to a request for comment. Baldwin and the weapons supervisor on the set of the film were charged last month with felony involuntary manslaughter in the shooting death of cinematographer Halyna Hutchins.