Amends the Criminal Code of 2012. Provides that the Public Act may be referred to as the Safe Firearm Storage Act. Provides that it is unlawful for any person to store or leave a firearm outside of that person's immediate possession or control (rather than within premises under his or her control if the person knows or has reason to believe that a minor under the age of 14 years who does not have a Firearm Owners Identification Card is likely to gain access to the firearm without the lawful permission of the minor's parent, guardian, or person having charge of the minor, and the minor causes death or great bodily harm with the firearm) unless the firearm is secured in a manner that renders it inaccessible to anyone but the owner or another lawfully authorized user: (1) by a device or mechanism, other than the firearm safety, designed to render a firearm temporarily inoperable; or (2) locked box or container. Deletes provisions that the law does not apply: (1) if a minor under 14 years of age gains access to a firearm and uses it in a lawful act of self-defense or defense of another; or (2) to any firearm obtained by a minor under the age of 14 because of an unlawful entry of the premises by the minor or another person. Deletes a provision that the firearm may be placed in some other location that a reasonable person would believe to be secure from a minor under the age of 14 years. Effective January 1, 2025.