I sent my 649 (1 7/8" barrel .38spl) to Karl Sokol in VT. He opened up the rear notch and sand blasted the top strap to reduce glare. He also cut the front sight blade to put in a red insert. I had sent my gun to a company that intalls the XS big dot sights a few years back but that didn't work out. They had the gun for a long time and the work never got done. I would have preferred the big dot tritium sights but opening up the rear notch really helps in acquiring the front sight. If you can get XS big dot 24/7's on your gun, do it. If not, you should consider having that rear notch opened up. Hope this helps.

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