Yes, the forcing cone ...is the rear portion of the barrel..at the cyclinder end...and it is slightly tapered so its easier for the bullet to enter the forcing cone ...as it emerges from the cyclinder.
By the way ....that carbon build up around the forcing cone --- can be cleaned up ...and if you stay after it, after every time you shoot it ....it'll look way better !!
I agree 1974 is what my book says ...
I only shoot the traditional 158 gr bullets in all of my K frame S&W's ( model 19's or 66's )...and I reload ....but there is a good variety of ammo available in 158gr...