In the 70's, Bushnel made a changing reticle scope in their low powered, 'Custom' line or 2 1/2X scopes, called "Command Post".

Turing a rear ring snapped the post, clockwise up, counterclockwise down. It was flat topped and stuck up just over the centre of the horizontal hair, just as the pointed version above does. They were meant for closer range rifles.

I had one for a time on a Mauser .458 - worked very well and was not the least bit intimidated with that rifle's recoil.