Suggest you call it body armor or maybe a ballistic vest. The term “bulletproof vest” is a misnomer since it isn’t entirely true!
PACA is a decent brand. At one time both the FBI and the Secret Service used it.
The hard trauma plate can cause bullet splatter, which can go into your throat area. However, PACA used to supply a rather small and pitiful plastic-coated steel plate that wouldn’t stop most rounds anyway (I’ve shot up a number of their plates and the bullets tend to either punch through or to make a deep dent, rather than ricochet).
Small plates such as the above were intended to protect from blunt trauma such as the impact from a steering wheel during an automobile crash, rather than from bullets.
However, many if not nearly all plates nowadays do have ballistic capabilities – thus the ricochet danger is much greater. These plates are often wrapped in Kevlar or such to minimize this.
Definitely wear the plate if you’ve got it and if it’s practical for what you’re doing. Note that larger trauma plates are very cumbersome.
Any vest will stop a regular .22 LR. In fact, that was one of the test rounds for the long obsolete level I vests. Note though that most soft vests won’t stop edged or pointed weapons such as slender knives, ice picks, and such. (Prison guards wear a different type of vest for this reason.)
In my limited experience, Kevlar does not appear to have a shelf life, per se. However, it will certainly deteriorate from usage or abuse.
Five years is the typical standard applied to Kevlar, and is used by vest manufacturers for the warranty. However, I’ve shot Kevlar vests that were well over 10 years old (but not heavily worn) in unscientific tests with no problems.
Vests are pretty easy to spot if you’re looking for them. If this is a big issue, you might want to consider a thinner level IIA
and a premium (and more expensive) vest. However, IIA’s don’t offer much margin for safety - if you’re getting a used vest, an II or even an IIIA is a better way to go. Not many folks wear IIA’s any more, anyway.
I’ve never dealt with these folks, but they appear to be reputable:
www.bulletproofme.comAs already mentioned, absolutely stay away from vests made from Zylon (or Second Chance’s trademark for it, which is Ultima), regardless of manufacturer!!