The slide has a 8-9 digit number stamped next to the plunger.
The barrel has 9X19 stamped on top of the barrel with a tiny pentagon icon right next to it.
Underneath the barrel on the ramp there is an odd 1mm x 6mm dotted rectangular matrix stamped on it.

I have owned many Glocks and this is a first....

Wassup' with dis?

Is there anhinga on the bottom of the trigger guard .

?





 

The longer number is a production tracking number. The pentagon symbol is supposedly a marking required under German/Austrian law which denotes the grade of the steel that the barrel is made of. Early barrels have simply a pentagon marking, recent barrels have a pentagon with a dot inside of it. I own one of each barrel and the "dotted pentagon" barrels are obviously a harder steel. The "dot matrix" is also supposed to be a production tracking number.

I always thought the pentagon on the barrel signified that the rifling was polygonal rather than land and groove.