Originally Posted by JP@AK
Those are what I refer to as "machined steel" washers, and they have not been blued. Some, I believe slightly later, came with the machined washers that are blued. After the war, the machined retaining washers were dropped in favor of stamped steel, and those also had a blue finish.
If I'm reading the serial number on yours correctly, it starts with an 8. It that case, these originally shipped on a postwar M&P revolver. That is the only possibility for a number this high. Could you please type in the actual serial number, in case I'm not reading it correctly? I would like to add these to my postwar M&P database.
Oh my, I have a postwar M&P. SN C3816xx