please ı look every video but is not working please help!
unreal engine 4 final version 2021
No such thing exists 
What do you mean by ‘ammo system’ - what features are you after, specifically? There’s a metric ton of various tutorials on how to make all kinds of ammo counters, reloading, shooting, funky bullet things out there:
https://www.youtube.com/results?search_query=ue4+ammo
You might as well have said, ‘how to make guns’ - what are we supposed to do with a question like that?