Subj. IIRC for "fragmentation" to happen, a round has to pass through a piece of armor first. Previous wipes, this wasn't a big deal as most decent rounds would kill you in one headshot or 2 chest shots anyways, so it was popular to wear a PACA or a Tac-Kek to defeat buckshot pellets, give a chance of a headshot ricochet, and reduce incoming damage by a bit.
Now, however, the cost/benefit may not be so simple due to damage falloff. A headshot with armor-piercing 5.56 or 5.45 won't kill you past a certain range (90-210m) due to damage falloff… unless you're wearing a Tac-Kek in which case you have 32-40% chance of being oneshot headshotted (minus whatever the ricochet chance is). Likewise for PACA: depending on range and round, you should die in 3-4 hits with intermediate calibers, but with PACA this will most likely be 2 hits as long as one of the rounds fragments (roughly 55% chance of either one doing so). Even class 3 armor is a bit questionable if facing someone firing M995 and such. Class 4 is very good against snipers however, as even M995 only has 36 pen at 200m, and everything weaker can be mostly shrugged off.
tl;dr : When going on sniper-heavy maps like Lighthouse, don't wear light armor it probably hurts you more than it helps (not to mention extra weight and cost)
