You have an M&P model, properly known as a 32 Winchester Hand Ejector, Military & Police, Model 1905, 1st or 2nd Change?? They were made from 1906 to 1909 in serial number range 22,427 to 45,200. Your revolver should have shipped around 1909 making it a 2nd Change as you stated, BUT if there is no patent date on the rebound slide, it is technically a 1st Change.
Apparently, there were no records to determine the exact year when the model changed from 1st to 2nd. One strong possibility is that these two models intermixed and that there was a transition between the 1st and 2nd Change over these 4 years.