Big Bore pressure Vs small bore pressure??

Assume we load a 458 Lott and 300 Wby to the same pressure or a 458 Win and 257 Wby to the same pressure. Also assume the amount of powder being used in both big and small bores is the same.

Then if the peak pressure is the same for both big and small bores the average pressure will be higher with the small bores and by a considerable margin.

Is that a factor?