A damage system I was thinking about for gritty RPG combat

I have been thinking about a gritty penetration-based, hit-point-less damage system for grittier RPG combat. The came to me when thinking about my Cepheus Atom rules, where you have "hit-point-equivalents" (Endurance and Lifeblood), but, in practice, you have wound levels based on these "hit points": Uninjured, Lightly Injured, Seriously Injured, and Dead. So, why should I use the wound levels directly, instead of going through the "hit points"?

So...

Let's use Cepheus Light vehicle damage as an inspiration. Weapons have Penetration Dice. Ordinary handguns, knives, spears, etc. have 1d6. Rifles, light machine guns, big-ass pistols, long/bastard swords, etc. have 2d6. Sniper rifles, medium machine guns, grenade blasts, and broadswords have 3d6. Really heavy stuff such as RPG-7s and big lasers have 4d6.

Once you hit a target, you roll the penetration dice: 1-2 no damage; 3-5 light wound; 6-8 to severe wound; 9-11 mortally wound; or 12+ insta-kill.

Armor is a penalty to the penetration roll. Light armor is -3, heavy armor is -6, powered armor is -9.

A critical hit (let's say, a natural 12 on the 2d6 attack roll) adds one Penetration Die.

So, the probabilities of the various wound levels, once a hit is made, are (I hope I got the math right...):

Pistol vs. unarmored target:

33% flesh wound (no game effect)

50% light wound

17% serious wound

No mortal wound or insta-kill without crit.

Rifle vs. unarmored target:

8% flesh wound

33% light wound

42% serious wound

15% mortal wound

2% insta-kill

With light armor (-3 to the roll):

Pistol:

85% flesh wound

16% light wound

No serious+ wounds without crit.

Rifle:

27% flesh wound

56% light wound

15% serious wound

2% mortal wound

With heavy armor (-6 to the roll):

Pistol:

No damage unless on a crit.

Rifle:

73% flesh wound

25% light wound

2% serious wound

Now, let's factor in the to-hit chance: 8+ on 2d6 + attacker skill - target skill and assume equal skills, per shot fired:

Unarmored/Pistol:

71% miss or flesh wound (no game-relevant damage)

21% light wound

7% serious wound

Unarmored/Rifle:

61% miss or flesh wound (no game-relevant damage)

14% light wound

17% serious wound

6% mortal wound

1% insta-kill

With (common) light armor:

Pistol:

93% miss or flesh wound

7% light wound

Rifle:

69% miss or flesh wound

23% light wound

6% serious wound

1% mortal wound

What do you think of this system? Is it too lethal? Does it "feel" well in play?