The only one I know was the hit on the guy who was presumed to have killed Carlo Gambino's nephew. However, it later turned out that someone else had actually killed Gambino's cousin.

Gotti also got the contract to murder Roy DeMeo, but he pased that one to someone else as he apparantly feared the DeMeo crew too much.

He probably participated in a few more hits and he surely had beaten up a lot of guys.