off topic - love to know how that got there - sabot projectile

[Olefin]

“On 10/22/17 at 1325 hours, Harrisburg Police were flagged down by a jogger on the Front Street River Walk at Peffer Street. The jogger advised the officer of a strange object in the river bank. Officers identified the object as a possible tank Sabot projectile. The area was secured and notification to the Pennsylvania State Police (PSP) Bomb Squad was made.

At 1531 hours, PSP bomb technicians arrived and confirmed that the object was a Sabot projectile. The projectile was collected and taken into custody by PSP. An HPD bomb K-9 was summoned after the projectile was secured to verify that there were no other explosives in the area. No other objects were found."

Ok heard of losing a lot of stuff but a sabot projectile just randomly ends up in the river?