So, just to wrap this up, here's the sequence:
c. 1931 - K-22 Outdoorsman's (note the possessive). It is distinctive because of the tiny adjustable rear sight as well as the round barrel with no rib.
1940 - K-22 Masterpiece First Model. As BD stated, this was only made for one year, and then the war broke out. I believe this was the first appearance of the Micro-adjustable rear sight.
1946 - K-22 Masterpiece Second Model. Micro-adjustable rear sight, ribbed barrel, five screw frame.
1956 - K-22 Masterpiece, four screw variation.
c. 1958 - Model 17 K-22 Masterpiece. Still four screws.
1959 - Model 17-1 K-22 Masterpiece. Four screws, extractor rod threads changed to left hand.
1961 - Model 17-2 K-22 Masterpiece. Reengineered cylinder stop, resulting in the elimination of the fourth screw; start of the three screw frame.
1967 - Model 17-3 K-22 Masterpiece. Rear sight leaf screw moved away from the barrel/cylinder gap.
1977 - Model 17-4 K-22 Masterpiece. Allegedly, this change involved the relocation of the gas ring. There remains some debate as to whether all 17-3 units had it on the yoke, but officially it moved to the cylinder with the -4 variation. It seems to me there is very little difference between a -3 and a -4;
until 1982, when the pinned barrel was eliminated.
I refuse to discuss anything after 1982. The Model 17 line just gets weird after that, in my opinion. And yes, opinions are like armpits. Everyone has two and they all stink, including mine.
Did I miss anything, Mr. Green?
Incidentally, sometime around 1950 or a bit later, the original narrow rib got a tiny bit wider and the barrel profile changed, eliminating the flare just ahead of the forward frame bridge. I don't know exactly when this happened. I would love to know, if anyone has that information.