An NYPD instructor was struck by his own gunfire at the department’s gun range in The Bronx on Thursday — the second time the cop was nailed by a ricocheting piece of bullet in a month, sources said.

Police Officer Eric Single was working at the range when he fired a rifle and the bullet hit a stanchion, sending a fragment flying into his leg at 11:30 p.m., sources said.

The cop was taken to Jacobi Medical Center, where he was listed in stable condition. The bullet shard is still in the cop’s thigh, where it’s expected to work its way out on its own without surgery, sources said.

Single suffered a similar injury at the Rodman’s Neck gun range July 10, again from a richocheting bullet. It’s unclear whether he fired that round also.