In world of Tenet, during the normal flow of time this bullet was first made in factory and then kept moving forward through timeline as object and increasing its entropy. But then it got into turnstile and kept moving backwards through time as object. Going back through timeline it'll overlap with that very moment in normal time flow where it still wasn't made in factory. Like we talking few nanoseconds before it was formed in bullet assembly machine. So basically it'd literally just disappear from existence at that very moment before it was shaped in normal flow of time? Like it'd just blink away in front of your eyes, like magic trick. That's seriously breaking laws of physics bit too much.