Slowhand.....1980 was the year S&W changed over from pinned barrels to non-pinned barrels on the model 10.....
I have a 10-8 in 4 inch that is pinned....It was one of the last ones made that way when they changed over that year in 1980....
My son has a 10-8 in 4 inch that is non-pinned...both...