From The Milwaukee Journal Sentinel:

_Transportation authorities say a passenger inadvertently carried shotgun shells onto a plane at Milwaukee’s Mitchell International Airport. . . .

_[According to another passenger] the pilot came on the intercom and said the plane had to return to the gate because a passenger had told a flight attendant he had the shells in his carry-on bag. . . .

The TSA statement says agents turned the ammunition over to local police. The man was rescreened and allowed back on the plane.