Not sure if it helps, but this is currently being advertised as a "genuine" item on Ebay: ✚8719✚ German Luftwaffe Flak Gunner Anti Aircraft Badge post WW2 1957 pattern | eBay I can see some slight differences in details but repro`s are so hard to distinguish sometimes.
The item shown above is not the same item as the one that you are asking about. This is a 1957 post war award that was issued without the swastika. Your award would have been issued during the war years. It's very difficult to tell from a photograph of this is correct, the casting looks to be of good quality but the wear marks on the back don't look consistent to the norm. I would suggest taking it to a dealer to take a closer look. Good luck. Hope it turns out to be good.