Either pick up the book on shooting by Alan Egusa or take a class from turnipseedtechnique.com or quickshoot.com.
You don't shoot effectively with bullseye, Weaver, modified Weaver FBI squat, or two arms straight out and expect consistency or accuracy.
You need an understanding of human ergonomics. Turnipseed teaches it as well as Egusa.
Practice, practice, practice is unavailing when you are doing things are ergonomically incorrect.
Whether it is martial arts, dance, professional boxing, baseball, football or shooting, you need an understanding of ergonomics.
Can you shoot and reload while running? You cannot do it with the stances I indicated above. So take the time and learn a stance that is good walking, running, or standing still.