I now own four 3rd generation glocks models 17, 22, 35, and just bought a 23. Upon feild stripping my new g23 I noticed that the top of the frame (where the rails are) is polished and that there is also a ten digit number (not the serial number) stamped into the polished portion of the frame. Since I have noticed I have feild stripped all of the 19's and 23's (couldn't find a 32) I could get my hands on and all were polished but only about half had the stamped number. I am very curious as to what the number means and why the top of the frame is polished on the compacts only and not my other models. I also noticed that the slide rides slightly higher off of the frame then it does my others as well. If anyone could tell me I would really apprechiate it.