Help needed from Firearm guru's and armor junkies, Need to make pistol/armor for RPG Options

[Stumps]

Ok...I'm working on creating an RPG...(not all by myself)
At any rate, I need help designing the equivilant to a 9mm pistol and a piece of kevlar chest armor.

I want the pistol to be as realistic as possible.
So making it hurt isn't a bad thing here.

For the armor, I just need to figure out it's durability.
Like, what level of impact it can stand, and what level it gives in.
(or what caliber it can stand)

The armor works as follows in the game.
The bullet strikes the armor and all physical damage is taken by the armor.
The armor loses armor points everytime it takes a bullet.
Once the armor loses all of it's armor points the bullet(physical damage) goes to the defending character.
Even though the character is not receiving physical damage, they still receive a level of stun damage from the impact.
(this is just the basics so you can understand...there's more, but we don't need to go into that for this.)

Damage is straight damage in the game so far.
There is no comparing successes or the like yet, so the 9mm pistol can be straight conversion from caliber to game stat.

The Physical Damage bar is set at 10 boxes.

I would do this myself, but I don't know enough about this stuff yet.
I indeed could go research this and do it all myself, which I will do later, but right now I just need this one weapon and this one piece of armor.


Raygun?
Anyone?
Got any ideas of helpful comments?

(p.s. I'm not going to debate the core system here at all.)