Dayton James Webber -- the quadruple amputee who is accused of shooting another man to death in his car -- may have done so after an argument over a gun and a fight about a woman ... TMZ has learned. As you know ... Webber was arrested for the murder of  Bradrick Michael Wells last Sunday. Cops say eyewitnesses told them Webber shot Wells in Maryland, then asked them for help pushing his body out of the car. Officers say these eyewitnesses told them they refused, and they got out of Webber's