I’m in the market for a mod. 457 and to that end am trying to learn as much as possible. I see someone with and without MIM hammers, some with steel and some with plastic guide rods, some with the S&W logo on the right side of the frame etc. What other changes am I missing, and when did these begin? I’m hoping to find one with the less “value” line parts, i.d. MIM and plastic, analogous to a 915 before it transitioned into the 910. Thank you.