Unless they have changed their 9mm NATO is not up to NATO specs 124gr NATO out of 4in bbl moves 1300fps theirs is slower. When you go next time look at the 115gr fps their 124gr moves just as fast or a little more than the 115gr and they call it 9mm NATO. If you get the real deal the stamp at the bottom of bullet will have a wwc, not to say they can't load 124gr to 1300fps.
Since the 9mm is small and moves fast in its FMJ configuration it zips straight through the body and no one stops attacking at least not right away. This is where shoot placement comes in, hit the three zones that make peolpe stop the 9mm will be just fine.
I had some real 9mm NATO shot it all up would like to shoot some more but 115gr is cheaper.
When you shoot 115gr and then 124gr you will be off some due to bullet weight if you have a zeroed pistol. But if you have your weapon for your personal protection and at the distances most self defense situations take place do not sweat it its not like you are trying to get 1 MOA out of your pistol.