Mandatory Minimum Sentence Reform Act This bill creates an exception to certain mandatory minimum sentencing requirements. Current law prohibits and imposes a mandatory minimum sentence for using, carrying, or possessing a firearm during a crime of violence. This bill excludes from the mandatory minimum sentencing requirement a federal employee outside the United States who is required to carry a firearm while on duty and who, while on duty, uses, carries, or possesses the firearm during a crime of violence.