TSA gun safe standards are fairly simple: the firearm must be in a hard-sided, locked case. The California Department of Justice (CDOJ) standards for gun safes are more stringent and include specifications like the number of possible combinations for a combination lock, thickness and number of locking bolts, and a minimum thickness of twelve-gauge steel for the shell. Many gun owners consider the CDOJ standards to be the minimum quality standards for gun safes. Visit TSA.gov to find out more about the guidelines for legally transporting firearms and ammunition by commercial airliner.