Yes. Some were 1/8" and others 1/10". I don't know when the change took place. No doubt the change was phased in, as they always seem to be.

As for the dates:

K3081x (five digits) would be early, probably shipped in 1948.
K15217x is from 1952. I show a bunch in that range that shipped in October of that year. But those are .38 Special (K-38), so I'm not sure how reliable that would be with respect to a K-22. Shipping dates can vary quite a bit from model to model. And you always need to remember that S&W didn't ship in serial order.

__________________
Jack
SWCA #2475, SWHF #318