http://www.youtube.com/watch?v=euj2RDiSZy0&feature=youtu.be
This mod again, allows you to aim ONLY the AK47 and M4 like Al Pacino Scarface. The installation is easy, just put the Weapon.dat into the Data folder in your GTAIII directory.
only thing you have to do is go to your weapon.dat and change the rifle's animation to the shotgun animation. i always do this with the AK because he looks funny shooting