Do I need a NM sight base to use a NM windage knob?

Thanks!

Yes, Unless the Knob has been modified with 8 detents .

I think that's pretty much standard with National Match windage knobs isn't it. They have the 4 extra adjustment positions. What does the NM sight base do to accomodate the NM windage knob?

A true traditional " NM " rear sight has a base and windage knob with a finer thread pitch so the sight moves half the distance per click compared to a standard base and knob.

The Army MU and especially the Air Force Marksmanship armorers swore by the modified standard wind knob with eight detents instead of the original four and a spring and ball or mod'd ectractor spring & detent in a hole drilled into the receiver under the knob ( SA Inc does this method on thier loaded M1a's ) The repeatability of the clicks is more consistant, repeatable and less backlash with this method they said.

Thanks.  I'm wanting some finer windage adjustments on a SA standard I'm getting.