Could anyone tell me approximately when Smith & Wesson quit using the full blade/half moon front sight on the 2" Bbl. M&P ? I recently acquired a two-incher (C352xxx) that lettered to Mar. 14, 1956. It has the "newest" hammer (flatter, sharp-toothed spur), but the old, full blade front sight (Bbl. is numbered to gun.) Thanks so much for any info.!! - webley6