As the man moved through the checkpoint, a scanner alarmed in his groin area where the shotgun shell was found under his clothing, TSA said.
The white powder found inside the modified shell was tested and found to be methamphetamine.
The man, who was not named but identified as an Orangeville, PA resident, was arrested by Philadelphia police, according to the TSA.
Shotgun shells and any caliber of ammunition are prohibited from being carried through a security checkpoint.
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