Photo by Rab Cummings
Chamber flags are great tools to indicate the status of a gun. They give a clear visual that a firearm action is not in a position to be discharged. Not only are they handy for the person handling the firearm, but they also send a signal to others in the vicinity that the gun is not charged. Some ranges and competitions even require their use.
The way chamber flags are traditionally used, the stem on the flag is inserted into the chamber. This is fine if your gun is cold, but insert a flag with a thin stem into the chamber of an AR that you just put 100 rounds through quickly, and you could end up with a molten mess of plastic.
Instead, run the stem of the flag through the magazine well. This prevents the plastic from coming in contact with hot metal and does just as good a job of broadcasting that the rifle isn’t loaded.