Swap between Buffington and ramp backsights?

[Patrick Chadwick]

What a strange idea! Slotless screws! I cannot think of another example, and can only surmise that someone thought it was a clever trick to prevent non-armory personnel from removing the sights. Like the "reversed" screw heads on the Enfield No. 4 foresight, which, as Peter Laidler informs us, were often enough replaced with normal screws by the armorers if the original was FUBARed!