The fragments are from some of the 22 reported shootings along roadways in four southeastern Michigan counties over a three-day period.
"At my forensic science lab they have been able to tie seven of the bullet fragments, six in Wixom and to the same gun, and intuitively we believe they are all from the same gun," said Oakland County Sheriff Michael Bouchard.
No one has been hit in the shootings, which happened Oct. 16 through last Thursday, but bullets have hit cars.
A specially formed task force with dozens of investigators has been working to solve the shootings that have happened in Ingham County, Oakland County, Livingston County and Shiawassee County.
Ten of the incidents happened in Wixom alone.
Police say they are searching for a man using a semi-automatic handgun, not a rifle.
Police have a sketch of a suspect described as a young man with closely cropped hair who was driving a black sedan, possibly a Chevrolet/Oldsmobile Alero or Toyota Camry.
"Turn yourself in," said Bouchard. "No one has been hurt. No one's been killed. Now is the time to stop. It would show the court or the system that you recognize you've done wrong."