what is a barrel flag?
A barrel flag is an orange zip tie with a piece of orange duct tape at one end. You put the zip tie into the barrel through the action so that the little orange duct tape flag can be seen sticking out of the action.
Impossible for the gun to be in an unsafe condition with the barrel flag in the gun. It’s AWESOME if you are an Range Safety Officer on an open outdoor gun range, because you can look down a row of shooters and see the flags sticking out of the actions of the guns.