Are you looking to make a bigger shoulder turn in your backswing? If so, try this drill next time you are on the practice range.
Simply take your backswing and stop, as illustrated in the first picture. Once you have stopped, take a look behind yourself. As you rotate your head to the right to look behind yourself, your shoulder turn will increase significantly. Notice how much my shoulder turn increased once I looked behind myself. Do this several times in your practice swings and you will be amazed at the increase in your shoulder turn.
A bigger turn equates to more power without swinging harder at the ball. A bigger shoulder turn also ensures better body positioning, enabling you to become more consistent in your ball striking.
Good luck and practice hard!!