BTW - All threat level II vests - or "Soft Body Armour" as they are properly known as, are for handgun rounds only. They are not capable of withstanding anything more.
I conducted a ballistics test on a vest for my Department one time.
I fired .44mag, .44 spec., .357 158grn and 125 grn JHP, .45 auto 230 grn ball., .38 spec. 158 grn LHP and round nose 158 grn, and 9mm 115 grn JHP and 124 grn Ball.
This was about 18 years ago using a level II vest with bundled news papers as backing.
The .38's,9 mm,.45 and .44 spec. put a dimple in the vest with the dimple getting bigger with weight, and a small indentation in the backing.
The .357 158grn penetrated about 1/3 of the way through the vest and did noticeable damage to the backing. (this is called "Blunt Trama")
The 125grn .357 was the Remington Peters round (my favorite at that time). It penetrated over half way through the panel and did greater damage to the backing.
The daddy load - .44 mag, 240 grn JHP penetrated almost through the vest and did massive damage to the backing.
To put in into perspective the amount of damage to the paper was about the size of your fist. Complete disruption.
The same would happen to a body.
It actually might be enough to kill you even with no penetration.
I have heard of this with shotgun slugs.
Now - the Kevlar will degrade in tensile strength with age and exposure to ultraviolet rays. After five years most Departments will replace a vest. Some will go 10 years if not worn much and kept in a closet or locker.
Also a vest that has been completely soaked temporarily loses some of its tensile strength.