Chagrin... I think you misunderstood...your answer is so obvious that I'm not sure what you were even answering.
I'm looking for the screw size that would fit through the holes in the arms of the servo horn. Zoom, I'm going to try to check in the RC stores... do you know what they market them as? Is there a special name for them? "Servo horn screws" seem to always refer to the screw in the center that holds it in place. I'm looking for the screws that would allow me to actually attach something to it.
(I'll still try checking those stores again, I very well could have overlooked that because I don't remember seeing anything close to that)