I miss my old 645. Bought it in Germany in 88. Shipped it home, and eventually traded it in about 93 for a Ruger SR9. Worst decision I ever made. It had Novak sights on it before Novak started selling the new sights to S&W for the 4506. Sigh.
I had one of the first S&W Mod. #645 I built while attending the S & W Armorers School in Mass. many years ago. It had a very distinct serial number 64501 I gave it to my oldest son about 3 years ago and it will pass on down in the family.