Print out a copy of TSA regulations and keep it in your possession. I have run into power tripping counter help and TSA agents that have no clue what the regulations are. Be prepared to produce the document and show them the exact regs that come from their web site. Last time I looked the airlines may require a lock in every position, but not the TSA. TSA regs say that the "container must completely secure the firearm from being accessed." If you travel enough you WILL ENCOUNTER AN AIRLINE EMPLOYEE OR TSA AGENT THAT WANTS TO MAKE AN ISSUE WHERE THERE ISN'T ONE. Be prepared for it.