For reference, here a basic break down of the Model 10's (Data derived from multiple reference sources) - Enjoy!

S&W Model 10's Variant Matrix

Model: Year: -- Design/Engineering Changes: -- Frame Screws:
10 ----- 1957 -- Start of Model Numbering / Tapered Barrel -- 4 Screw
10-1 --- 1959 -- Introduction of Heavy Barrel -- 4 Screw
10-2 --- 1961 -- Internal Engineering Changes on Tapered Barrel Version -- 4 Screw
10-3 --- 1961 -- Int. Eng. And Sight Change on Heavy Barrel Version -- 4 Screw
10-4 --- 1962 -- Eliminated Trigger Guard Screw on Tapered Barrel Version -- 3 Screw
10-5 --- 1962 -- Rear Sight Change on Tapered Barrel Version -- 3 Screw
10-6 --- 1962 -- Eliminated Trigger Guard Screw on Heavy Barrel Version -- 3 Screw
10-7 --- 1977 -- Gas Ring Change on Tapered Barrel Version -- 3 Screw
10-8 --- 1977 -- Gas Ring Change on Heavy Barrel Version -- 3 Screw
10-9 --- 1988 -- Yoke Change/Floating Firing Pin Change on Tapered Barrel -- 3 Screw
10-10 -- 1988 -- Yoke Change/Floating Firing Pin Change on Heavy Barrel -- 3 Screw
10-11 -- 1997 -- Int. Eng. and Frame Change/MIM Hammer on Tapered Barrel Version -- 3 Screw
10-12 -- 1997 -- Int. Eng. and Frame Change/MIM Hammer on Heavy Barrel Version -- 3 Screw
10-13 -- 2002 -- 1899 100th Year Anniversary Commemorative -- 3 Screw
10-14 -- 2002 -- Introduction of Internal Key Lock / Heavy Barrel Only -- 3 Screw

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Cheers....Obi-GUN