IIRC the K22 was introduced in 1931,
The only consistent thing about the K22 was the constant small changes made to them which is what makes them so fun to collect.

I have most of the variations from introduction up until the 17-8 PC Heritage gun which is a retro tribute to the early K22 Outdoorsman.

Perhaps one day will do a thread on the six inch K22 evolution ,
Did a thread on the 4" Combat Masterpiece evolution from 1949 to about 1990 if interested here's a link.

Some Combat Masterpiece eye candy