Anschutz (JGA) made many different models of these Karabiners for indoor training purposes. Many in .22 rimfire, some in other calibers.
'Glatt' translates to 'oily' or 'lubricated', similar to our older designation of '.22LR Outside-Lubricated.'
In all probability, your rifle is chambered for the standard 9mm European rimfire which is still commercially loaded by Fiocchi. Have a chamber cast made to be sure.