While it will be quite bloody and gruesome, making combat even more violent, it may just lead to some amazing stories of heroism, with PCs with shattered bones and massive blood loss somehow clinging to life and pulling through, despite the odds.
It will also lead to a lot more characters being rolled up. :)
Whenever a character has been shot, roll 2d6 to determine where the shot hit (or, even better, get the players to state where they're aiming and adjust the difficulty).
2-4 head
5-6 chest
7-8 abdomen
9-10 limb (1-3 leg, 4-6 arm, 1-3 right, 4-6 left)
11 pelvis
12 neck
After that, just check the damage done and whether the character is wearing any form of armour in that location, then check up to see the what damage level dealt.
1-6 light -2
7-12 medium no modification
13-18 heavy +2
19+ very heavy +4
Now, roll 2d6 + the damage level modification on the following charts to determine the injury dealt to the character (yeah, this system is full of charts, get over it!).
Head
1 and less: Scalp wound. Heavy bleeding
2-5: Cracked jaw. 20% chance victim cannot breath. Light bleeding, unable to close mouth properly.
7-9: Face wound. Several bones damaged, 50% chance extreme haemorrhage, lots of shock, face paralysed.
10-12: Bad scalp wound. Extreme haemorrhage, heavy bleeding.
13+: Skull fracture. Blood leaking from ears/nose/throat, blood in white of eyes, loss of vision in one eye, loss of smell, lose consciousness in 2d6 rounds. 80% chance enter coma, if not almost instantaneous death.
Neck (all 50% chance damage to neck muscles, unable to hold head upright)
1 and less:Brachial Plexis damaged. Numbness and partial paralysis in either left or right arm.
2-3: Stellate Ganglion damaged. Pupils dilated, loss of long vision.
4-6: Jugular wounded. Heavy bleeding and hypolovemic shock.
7-8: Cranial nerves. Unable to shrug shoulders or rotate chin, tongue paralysed, hoarseness, difficulty in swallowing.
9-11: Spinal cord. Paralysis.
12+: Larynx and Trachea. Spitting blood, sucking neck wound, difficulty with breathing, high-pitched, noisy respiration.
Chest
2 and less: Ribs fractured. Difficulty in breathing, making it hard to do any exerting activity.
3-6: Collar bone/shoulder blade damaged. Unable to move arm unless splinted, and a lot of pain with any type of activity.
7-9: Sucking chest wound.
10-12: Tension Pneumothorax. Victim unable to breath, pass out in about fifteen minutes, and will suffocate if not treated.
13+: Heart. Massive blood loss, heart failure. Very quick death.
Abdomen (80% chance localised pain, nausea and reflex vomiting)
2 and less: Stomach muscles. Great pain, almost impossible to do most things without immense amounts of pain.
3-5: Blood vessels. Cuts off supply to leg, making it impossible to stand very soon, and may cause severe swelling in the leg.
6-7: Intestines. After a day or two after receiving the injury, severe pain, fever, vomiting and, if untreated, death in a week.
8-10: Bladder/kidney. 50% chance massive haemorrhage, otherwise long term renal failure, 50% chance fatal.
11+: Spleen/liver. Massive pain in upper abdomen, massive haemorrhage, shock and death very quickly if not treated.
Pelvic wounds
Unable to stand, 50% chance cuts off blood supply to leg, with heavy bleeding and haemorrhage.
Limb
3 and less: Extreme pain, hard to use limb.
4-7: Muscle damage. Very hard to use limb.
8-10: Bone cracked/shattered. Extreme pain, blood loss, Practically impossible to use limb.
11+: Massive haemorrhage.
Notes
Sucking Wounds: Victim will feel short of breath, air visibly sucked in through wound. Low oxygen will cause unconsciousness in ten minutes.
Bleeding and haemorrhage: Usually, if heavy, unconsciousness and death, very faint, suffering penalties to all activities.