X-24 is a clone of Wolverine. Wolverine is basically immortal if not for long term Adamantium poisoning. Wolverine, in one timeline, has been shot in the head with Adamantium with only minor effects. In the source material, he's been reduced to a single cell and regenerated. He's been decapitated and dismembered. Even with Adamantium limiting his healing factor, he's the hardest sob to kill in any universe.
So why does a single bullet shatter his head like that, killing X-24 instantly instead of regenerating? He should be able to regenerate in a few hours or days without a problem. After all, he has only been around and with Adamantium for months or years, no where near as long as the original (50 years of Adamantium until death, roughly) so he shouldn't have a compromised healing factor. Has production explained the discrepancy?