Three suspected machine guns were recovered after a man allegedly pulled a weapon on another motorist who he believed was following him in County Down, the High Court has heard.
Andrew Williamson, from Ashgrove Avenue, Banbridge, faces a number of charges.
The incident allegedly happened after Mr Williamson made contact with a girl on Facebook. She was the girlfriend of the motorist.
Mr Williamson was refused bail.
Weapons enthusiast Mr Williamson is accused of forcing the driver to stop, tapping his window with a handgun and asking if the man was following him.
The 23-year-old is charged with possessing a firearm or imitation firearm with intent to cause fear of violence.
He is also accused of carrying a firearm in a public place.
A judge refused him bail due to the risk of flouting release conditions or committing any further offences.
The charges relate to a motoring incident in Banbridge last Wednesday night.
A prosecuting lawyer said the alleged victim was in a car travelling behind Mr Williamson's vehicle.
At one stage the accused stopped and blocked the other man's path.
Crown counsel Christine Smith said it was alleged that Mr Williamson then got out, approached the other car and tapped the window with a black handgun.
He was said to have inquired if the man was following him, was told "no", and then returned to his car and drove off.
Police searches of his home later that night led to the recovery of three suspected machine guns and a handgun, the court heard.
Following his arrest Mr Williamson denied any involvement in the incident.
He said the handgun was blank-firing, and that the other three weapons - for which he had certificates - were deactivated.
All of the suspected weapons are to be forensically examined.
Michael Boyd, defending, confirmed his client claimed he did not know the other man but had added his girlfriend as a friend on Facebook weeks earlier.
The barrister also disclosed that Mr Williamson had posted pictures of himself with some of his weapons on the site.
"He is a gun enthusiast with a hobby in collecting old, deactivated weapons," Mr Boyd said.
"He has certificates for the weapons recovered from his house."
Mr Justice Hart refused bail.
"The circumstances giving rise to these allegations undoubtedly suggest this young man is capable of behaving in a very eccentric and frightening fashion towards others," he said.