I may be wrong but with the factory remington action, you have to cut a counterbore into the barrel for the bolt nose, the part of the bolt that extends past the locking lugs.
Perhaps those actions have the locking lugs are more forward and inline with the bolt face meaning you wouldn't want a counterbore in the barrel
That`s right. Remington breech is recessed for the bolt nose. There is actually a few rifles that have flat breech designs, Montana, mauser 98,post 64 win 70, etc.