I have read several posts mentioning GC behind case neck, .357Sig, 7.62x39, 5.45x39, etc. As though this "Is a had thing". Having the bullet take up usually empty spade has been proven to raise chamber pressure. (A.357Sig loaded with any 124gr bullet j-word of lead has that condition.) So other than increased pressure what is bad about having GC behind the neck? Scientific evidence would be appreciated.