SN butt 30.jpg 19 four-screw left.jpg
19 four-screw right.jpg 19 four-screw cylinder rear.jpg

I recently purchased a S&W revolver that seems to be a "Pre-Model 19." It has the screw at the front of the trigger guard. It is not marked as "Combat Magnum."
The serial number on the butt is K260692, repeated on the rear of the cylinder.
There is an apparently unrelated number and the letter "Y" on the frame under the yoke.
Looking up "Combat Magnum" in the SCofS&W 3rd Edition, on page 136 production dates are shown as "1955 - 1999," with the moniker "Model 19" given them from 1957 on. Introductory serial number is shown as "K260001."
THEN, I go to the serial number section of the book, page 398, and find this one falls into the year 1955.
And THEN I go to page 186 where I find "Model 19 serial number K33333 attributed to J. Egdar Hoover." Wouldn't that be WAY before the range shown for the Model 19? Page 398 seems to indicate it was from 1948.
AND, on page 185, production dates for the Model 19 (presumably named such) are 1955 - 1999.
HELP!
pix attached (note the FABULOUS finish!)