No such thing as the "lock jaw factor"
""Pit Bulls have locking jaws." The jaws of the Pit Bull are functionally the same as the jaws of any other breed, and this has been proven via expert examination.
The few studies which have been conducted of the structure of the skulls, mandibles and teeth of Pit Bulls show that, in proportion to their size, their jaw structure and thus its inferred functional morphology, is no different than that of any [other] breed of dog. There is absolutely not evidence for the existence of any kind of ?locking mechanism? unique to the structure of the jaw and/or teeth of the American Pit Bull Terrier, says Dr. I. Lerh Brisbin of the University of Georgia (from the ADBA booklet, ?Discover the American Pit Bull Terrier.) "
"?Pit Bulls have more bite pressure per square inch (PSI) than any other breed.? This is pure speculation at best, damaging myth at worse. There have been no exhaustive studies conducted to prove that Pit Bulls have the strongest jaws of any breed. There likely could not be any truly conclusive testing done to measure something like strongest breed PSI. A reason for this lies in the fact that dogs bite with varying pressure depending upon the situation, and what factors are driving the bite at that particular point in time. A dog cannot be instructed to bite down on a measuring device as hard as possible, so a tester could have no way of knowing whether or not a particular dog being tested is actually using its jaws to capacity in any given testing phase. There is also large size variation in any breed, and one must assume strength varies as well. A very large (but not typical or standard) Pit Bull may bite harder than a small Rottweiler, German Shepherd, or other breed, while a standard sized Pit Bull may not have as much jaw power as a larger, typical sized Rottweiler, etc. Also, if one breed is to claim ?highest bite pressure?, all breeds would have to be compared. All 500+ of them."
"14. How strong are a gray wolves' jaws?
The massive molars and powerful jaws of a wolf are used to crush the bones of its prey. The biting capacity of a wolf is 1,500 pounds of pressure per square inch. The strength of a wolf's jaws makes it possible to bite through a moose femur in six to eight bites. In comparison, a German shepherd has a biting pressure of 750 pounds per square inch. A human has a much lower biting pressure of 300 pounds per square inch."
The numbers are all over the place depending on what site you go to