According to Standard Catalog of Smith & Wesson by Supica and Nahas, the 10-7 change was made in 1977 - "Gas Ring change from yoke to cylinder on tapered barrel."
Originally posted by scha:
According to Standard Catalog of Smith & Wesson by Supica and Nahas, the 10-7 change was made in 1977 - "Gas Ring change from yoke to cylinder on tapered barrel."