For better of for worse, this is the comment section of a revenge power fantasy edge Lord manga, getting that far into the weeds of ballistics and energy transfer only comes into to play if it's necessary for the MC to win a fight, otherwise "bullet" is the "power" itself lol.
You can see...
I haven't read the WN, but Hyce uses a Minigun at least once in the story, which shoots .308/7.52x51. Before we even consider the effect of magic bullets, the armor piercing variant of this ammo, M80A1, can easily penetrate almost an inch of steel. So, I don't think a few centimeters matter...
Whenever I see a rant like this a count down for allegations of grooming minors on Discord or Roblox starts ticking.
They're always projecting and grandstanding.