The 1/8" Blanchard Red Ramp front sight was featured in the (October, 1952) first printing of the Centennial Catalog, 1852-1952
Advertised as a recent improvement of the Baughman Quick Draw front sight, Norman E. Blanchard, a former employee of S&W with 50 years of experience, effected a union of these two superb sights, which combined the best features of each. In the face of a serrated ramp, a piece of red luminous plastic has been inserted. "Thus you have a luminous red post front sight of quick draw type which has heretofore been considered a difficult combination to achieve."
S&W and Norman Blanchard supposedly had some sort of a falling out, and subsequent publications of the Centennial Catalog were devoid of the Blanchard front sight. The Baughman Quick Draw front sight with a red luminous plastic insert with a different shape than the Blanchard took its place.
A page from the S&W Centennial Catalog featuring the Blanchard FS has been attached. The photo of the 3.5" .357 Magnum I've attached, which shipped in January 1952, has the very rare Blanchard Red Ramp front sight. Many, many collectors have never seen one in the flesh. Beside the one I own, I have never handled another.