Good comments and questions Sigfla. Many Savagesmiths have used BillPA's fix.... and a fine one it is. Gunsmiths on the other hand, put the bolt body in the mill and shorten the bolt handle end of the body after taking some measurements. they may use the shim between the baffle and the rear of the action and remove that amount from the rear of the bolt body. Manufacturing tolerances on several dimensions and even wear can cause the problem.

If someone trues an action they may skim the lug abutments and they may touch off the rear of the bolt head. take too much and PE rears its head. The only fix is to shorten the rear of the bolt or to add material behind the rear action face in front of the rear baffle.
As for the reason savage used that method....Take a look at the rear of other manufacture actions. Look at the difficulty of machining. Savage cast a piece and is done with it. Remington has its share of PE issues. Ive seen many Rem. actions/rifles with changed bolts that have no PE.