1903 Different Elevation Screws

I have looked at a couple sources but can not find a reference for when the 1903 elevation locking screw changed from being dished to flat. Which one would be correct for what year?

I've been told late '18 into '19 as supplies were used up. I can not confirm or deny that claim with any facts at my disposal.

If you give us the serial number of your rifle, I can look and tell you which slide binding screw it should have.

J.B.