Does pitbull have bad lock jaw?

No. The pit bull does not have a locking jaw. They are a breed known for determination and willingness to please which is why they can grab on and play that great game of tug of war. They are no different then any other dog, in fact some scientists say that if their jaws did lock they would not be classified as canine anymore. Training and specialization with humans and other animals is essential with any dog.