I've owned several and seen several more bolt rifles with cocking-piece peeps, and all used some sort of centering method to ensure return to zero. The British and European rifles used the vee-notch method already shown while the US-made 1903s used the 2-pin method. I'm sure that other rifles used other methods but those are the two that I've seen.
Regards, Joe

You can lead a man to logic but you can't make him think. NRA Life since 1976. God bless America!