AzelleFans wrote...
..................... *observing*
...... Anyhow, is there any bullets that are able to pierce all body armors in existence? (handgun's or rifle's bullets)
Well I think anti-material ammunition probably would have enough power. Also autocannon ammunition would be more than enough. The problem is: Is it practical to use this ammo? (and also that they are not used in handguns)
I saw ceramic plate for additional ballistic defence for 7,62x51mm NATO (I held it in my hands). As far as military grade stuff they're not usually bulletproof vest, but flak-vests (which are not bulletproof) and they may or may not have pouches for additional ballistic protection (e.g. ceramic plates). Police are more prominent users of bulletproof vests.
The most penetrable cartridges I know in handguns are 7.62×25mm Tokarev and FN 5.7×28mm.
As far as rifle cartridges go as I stated above look in anti-material field and maybe even there you might go for more exotic ones like 14.5×114mm
Also .338 Lapua Magnum seems like possible cartridge that could do the trick.