Well, let's say this. First, a hit in a given location may
still do quite variable amounts of damage. Say you're shot in the arm with the 9mm. Is it just a grazing shot, a tiny scratch? Or did it go clean through, losing a lot of blood? Or did it strike a bone and rattle around inside for a horrible traumatic injury? There would still be a need to randomize that particular variable.
But probably more important is this: Hit locations have definitely been tried in the past by D&D and other RPG's and generally rejected as a horrible complicated mess. D&D first tried it in OD&D Supplement II, Blackmoor (1975; p. 7-12), and therein it goes on for 6 very dense and unplayable pages. First you need to decide if the attack is firing from the front, back, left, or right (separate tables for each). Also, in D&D you're not just fighting humans, consider the different body shape distributions: now you need tables for Humanoid, Reptile, Insectoid, Snake, Fish, and Avian. Considering the last two, now add attacker locations including "top" and "bottom". Now you have to have big blocks of text describing the different effects of amounts of damage on each body part of the different creature body types. Also, consider there's a lot of melee between creatures of radically different sizes (halflings vs. giants), which skews where people might hit -- now you need a giant 20x20 table for the "Weapon/Height Adjustment Matrix" which alters the percentages to hit each body type by relative size (halflings hit legs more often, heads more rarely, etc.)
Whew!
Executive summary is this: It's been tried lots of times over the past 30 years, and it's always been rejected by players as too complicated and unworkable. Who knows, you can get a free copy of Blackmoor as a PDF on Dave Arneson's website (
http://www.jovianclouds.com/blackmoor/bmc.html ), maybe you'll like it in your gaming.