Duane Brown was arrested on gun charges at the airport this weekend ... TMZ has learned.
The NFL free agent -- who was most recently playing offensive tackle for the Seattle Seahawks -- was busted Saturday at LAX around 2 PM, where law enforcement sources tell us ... he allegedly tried going through TSA with a gun in his luggage.
We're told this happened at Terminal 6, and that during the standard screening ... one of Brown's bags was found to have a firearm inside, which our sources say was unloaded.
Of course, the cops were called immediately .