I am confused when it comes to the serial numbers especially with the first three letters. I purchased yesterday a M&P 9 full size which has a serial number of MCPXXXX. On other forum sites, I see MPAXXXX and MPBXXXX. Does this mean mine is older? My firearm doesn't have the magazine safety or the internal lock. Are their serial numbers assigned to the options you get (magazine safety or internal lock)? Also how do I find out when my firearm was made? Any info. will be greatly appreciated.

For the DOB of your M&P check the date on the envelope containing the fired case that came with your gun.

My understanding of the 3 letter prefix is they started with MP and added letters of the alphabets until they reached Z. Then they started to use the alphabets over again but inserted it between M and P (MAP, MBP, MCP )