The first assistant director on “Rust,” David Halls, acknowledged to investigators that he should have checked a weapon for live rounds before giving it to Alec Baldwin, according to a search warrant affidavit filed on Wednesday. Baldwin fired the weapon while rehearsing a scene last Thursday at the Bonanza Creek Ranch near Santa Fe, striking cinematographer Halyna Hutchins and the director, Joel Souza. Hutchins was airlifted to a hospital in Albuquerque, where she died. Detectives had earlier disclosed that Halls declared the weapon was a “cold gun,” before giving it to Baldwin, meaning it did not contain live rounds. The affidavit filed on Wednesday includes new details from Halls’ interview with detectives, as well as details from an interview with Hannah Gutierrez Reed, the armorer on the film.