I never need anything more than my skinning knife to seperate the pelvis. after gaining access to the abdominal cavity, pull the intestines out of the way and put your finger down on the inside of the pelvis, you will feel a sharp ridge, this is called the pubic symphysis. using your finger to guide you where to put your knife directly on top of this ridge, then put pressure on the back of the blade with the hand not holding the knife it will split perfectly down the middle, but only if you have your knife lined up with the ridge. the pubic symphysis is a cartilage connection of the bones of the pelvis. I have found through no scientific means that the older a deer or other animal gets the less prominent the ridge is. I have split deer, elk & Moose using this method with my favorite skinning knife with a blade about 3" long. I have tried it on a black bear and got absolutely nowhere.