Doing some research to narrow in on identifying early 1905 4th Change M&P markings, 5 screw frame. Some had the large S&W logo on the right side (on the side plate) and some instead have a small S&W logo on the left side below the cylinder release with the side plate plain.

Noticed some are plain with no markings on the right side in front of the trigger guard, some say "Made in USA" or whatever.

Do any of these distinctions serve to date the revolver? I am sure they do if only someone knows.

I am looking to date a 6" M&P 1905, 4th change, no logo on the right side and no markings on the frame in front of the trigger guard.

Any help out there?