Pre-1980s 3” K-frames?

[jtcarm]

Yup, the only difference in those two engineering changes is the width of the front sight. The -4 had the 1/10" wide front sight (like the other earlier versions), while the -5 (and all subsequent engineering changes) has the 1/8" wide front sight.

Ooh! I love a 1/10" FS. 1/8" is too thick. Not enough light.