When you do the bolt thrust calculations the 30-30 case calculates to produce 75% of the thrust of the 8X56 case at equal pressures, so the maximum PSI for the 30-30 based round is 125% of what the maximum for the 8X56R is. The 8X56R is about 44,000 PSI, so the 58,000 PSI with the 30-30 case creates the same load on the bolt as the lower pressure 8X56R. Larry