Thanks for the welcome and the compliment on the revolver. I read the FAQs and answered my own question re. the keeper screw. (I assume this is what is referred to as the 'bug' screw found present on some early airweight models.) This one (S/N 418xx) is not an airweight, and, according to the Roy Jinks letter, was shipped in April, 1954. I got it new a few months later. Never been carried, seldom used. I've replaced it for carry with a M&P340, and it now lives in the safe.
John