Hi, I have a 6mm/243 with a slightly oversize chamber (headspace on fire formed brass measures 41,02mm as apposed to the more regular 40,96mm). When firing cases, the additional headspace leaves stretch marks on the cases (similar to excessive pressure). I am worried that these cases will eventually suffer from case head separation. Any ideas on how I can fire form new brass to avoid this issue? Any help/advice will be greatly appreciated!