Timothy A. Reilly, of, Silverdale, was arrested Friday and charged with terroristic threats, harassment, and disorderly conduct, the Central Bucks Regional Police Department said.
Reilly was "upset" after another driver merged in front of him sometime around 12:30 p.m. Friday, according to police.
He allegedly tailgated the car, sounded the horn, and gave the driver the middle finger.
While at a stoplight, the other motorist apparently saw Reilly shaking a gun at him, police said.
Reilly was released from custody after posting 10 percent of $10,000 bail, court records show.
His preliminary hearing is scheduled for March 1.
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