Found the answer to my own question. Probably should have searched a bit more before posting....
They are apparently to make for easier click count adjustments when only a half turn or less, one way or the other is needed.
Google is my friend.
Thanks for looking!
When the right to effective self-defence is denied, that right to self-defence which remains is essentially symbolic.
Freedom: Please enjoy responsibly.
Karma. Another word for revolver: because what goes around, comes around!