http://www.youtube.com/watch?v=C2fKGSEeD9g
The three-letter marking on the barrel that does not match the serial number is a date code that indicates the month and year of the proof testing in Austria.
Above the front of the trigger guard: http://www.gunforums.com/forums/fbbuploads/1264272830-G19_proof_marks.JPG
On the slide and barrel: http://www.glockfaq.com/content.aspx?ckey=Glock_FAQ_Serial_Numbers#austrian
The three-letter marking on the barrel that does not match the serial number is a date code that indicates the month and year of the proof testing in Austria.
Above the front of the trigger guard: http://www.gunforums.com/forums/fbbuploads/1264272830-G19_proof_marks.JPG
On the slide and barrel: http://www.glockfaq.com/content.aspx?ckey=Glock_FAQ_Serial_Numbers#austrian
