A teenage girl allegedly had a shotgun shoved in her face after mistakenly driving with her high beam headlights on in the NSW Hunter region over the weekend.

Police said the girl, 17, was driving along Aberglassyn Road at Rutherford about 10.20pm on Saturday unaware that she had turned on the high beam on her car's lights.

An 18-year-old man driving in a ute in front of the girl changed lanes, then began following the girl, police said.

The girl told police the two cars pulled to the side of the road and the man got out.

He allegedly walked up to the girl's car with a shotgun in his hands and exchanged words with two passengers sitting in the back, before pointing the gun into each window and repeatedly sliding the pump-action loader, police said.