Glock barrel markings

[Steelharp]

Anyone know what the 3D in an oval means? I know the pentagon with the dot meant it could handle +p+ ammo.

Also, what does AT stand for? Thanks.

[MPGlock]

Explanation from what I had been told in the past is that the 3D marking was a new government required marking in Austria and that the old markings were being phased out as supply of those barrels were used up. AT designates that the barrel was made in Austria. Again, this is what I was told last year (same markings on my g19 and had the same question on the 3D), so if someone has additional insight, please provide


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[tercel89]

Maybe this ? ....https://www.nist.gov/news-events/news/2016/07/nist-3d-ballistics-research-database-goes-live

[Erik88]

52 minutes ago, Steelharp said:

Anyone know what the 3D in an oval means? I know the pentagon with the dot meant it could handle +p+ ammo.

Also, what does AT stand for? Thanks.

Are you talking about a new or really old Glock? I had a Gen 2 19 and I believe it had ATT on the barrel which was a date code. The first letter was the month and the following 2 were the year. Maybe you're referring to something else? Mine was made in December of 88. 

[Steelharp]

On a Gen 4.