Where may I shoot an airgun in Cape Town
Depends on how far you are willing to travel.
As per above, Kraaifontein have a range of 75m available for air rifles. They are open Wednesdays, Fridays and Saturdays.
There is also Wetton Sport shooting club with a 45m + range that you can go to during the week or weekend, but will have to arrange and confirm with the caretaker.
I have been to Atlantis, but I did not enjoy the looooooooong stops when others want to walk up to 400m to check targets.