I am a new owner of a Glock 17 Gen4. I have a couple of other guns but have not been active in shooting for 20-30 years. I am going to class for a Concealed Handgun License in Texas in January so I got the Glock because of a recommendation from my son. I am wondering about the serial number of my gun. It has a '3 digit 3 number' group posted in several places on the gun and I thought that it might be the serial number, but the limitations of that grouping make this seem unlikely. I did find one 10 digit number under the slide after looking for a couple of days and I am assuming that it is the real serial number. Is this correct? I had thought that the US had some law requiring the serial number to be located in a specific place that was easily visible.