A baton round has been used to arrest a man who was reported to be holding a handgun and making threats to kill.
Sussex Police sealed off the area in Sompting on Thursday evening and 90 minutes later disarmed the 23-year-old.
The man was arrested on suspicion of possessing a firearm with intent to cause fear of violence.
Police said the weapon was found to be a ball-bearing gun and said the man also had an electronic stun gun. Officers said no-one was hurt.
The man remained in custody on Friday.