Of course not because a better bullet can always be built. The vest material is what decides what bullets it can stop well and no material is best for everything.
It depends on a lot of factors. The average layman might assume that the technology creates a "bullet-proof" garment, when in fact it's more bullet-resistant.
The type of vest, the type of weapon, the type of ammunition, the distance from which it's fired, the angle of fire, etc all play into the probability of protection.
