Nice work, though there are some things botheting me about it. First off all, the gun, its too curvy. Make it into a more modern weapon. Then the skin tone at the feet, its a bit different from the skin tone of the upper part, but maybe thats meant to be so... shades? You should do some color adjustments and work with light-shadow a little more, do some life drawing, that'll help .
But I like it that you put a personal touch and feeling into your piece. very good work .
The artist does not draw what he sees, but what he must make others see. - Edgar Degas