Strelok is correct. Your cartridge, which I assume does NOT have a hole in the tip, is a later version of the Dynamit A.-G./Geco Effectnose-Geschoß, which as imported into the USA was renamed by Check-Mate Arms Co., Inc. of Oak View, California, as the “Blitz Action Trauma” (BAT) cartridge. The initial designation for these rounds by DAG was "Effectnose-Geschoss (I am using the double SS in both instances printed as it appears on the original boxes). It was later changed to “Action-Geschoß,” and that began a long series of variations of this type of ammunition by DAG/GECO. The first version of the DAG/GECO cartridge was with projectile weight of 7,15 grams, later reduced to 5,6 grams. I suspect from the headstamp on your round that it is the latter, as the early rounds with commercial headstamps, said simply “GECO 9mm” with slightly later versions “GECO 9 mm Para.” The last commercial versions I saw of this specific variation (5.6 grams) were headstamped as is yours, “GECO 9 mm Luger.”
This round was introduced approximately 1976, according to an early dated box I have.
The “Deformationsgeschoß” which was introduced c. 1977 was a product of MEN , not Geco. The name was changed quickly in 1978 to Quick-Defense-Geschoss, again spelling from box labels. Interesting that the term “Quick-Defense” is expressed on the box as shown, in English.
Hope this is of some help.