contender hunter,
Please read my perviouse post! PSI is pounds per squaire inch, the lagrer tha case head the more suqare inches there are so the more total presure there is. the case head on a .204 is .378, so you mult. that by psi for total presure. If you have a .243, .22-250 or a .30-06 the case head is .473, so you would mult. that by PSI to get total presure.