Canon, there is not any hard fast rule in what pressures are between mag and standard cartridges. The saami psi listing for the 22-250, 6mm rem, 270 win, and 300 weatherby are all the same - 65000 psi. the 708 rem and 7mm rem mag likewise all list at 61000 psi. The brass at the web "may be" heavier but the larger area of the case head gives the pressure more area to work on. 65000 psi over .473" on a std case is not going to have the same effect as it will over .532" on a mag case.
