I was just starting to load my 500 smith with a new set of rcbs dies. They are steel not carbide. I lubed my hornady once fired brass and went to size and I could not size the case. I got the brass about 3/8" into the die and it got stuck. I lubed the inside and out like I always do. I looked in my manual and it says the mouth of the case is .530. My case is .530 as once fired brass. The inside of the die is .524. Any ideas?