Downswing Shoulder Drills?

I've noticed I slice my drives a lot because I pull my front shoulder (right shoulder, I'm a lefty) out early when on my downswing.

When I start my downswing my right shoulder is moving back instead of staying parallel.  This causes the ball to go wayyyyyy left of where I'm aiming because my arms/hands are being pulled to the inside of my swing line causing a massive slice.  I tried looking for some ideas on youtube and other places, but those videos seem to be more concerned with the backswing instead of the downswing.

I've noticed this is usually only a problem with my driver and 3wood.

Any ideas would be appreciated. Thanks a lot everyone!

I battle with this one too.

It helps me to think of sliding my hips forward while holding my head back.  The early opening of my shoulders on the downswing, causing that out-to-in swing path and pull/slice, brings with it an early move forward (down the target line) of my head.  If I move the hips forward while keeping my head behind the ball, it keeps my shoulders in check, drops the club into the slot, and I can fire through with a little push-draw (the shot I try to play).

-Andrew

I would agree with open face.  If you can get more axis tilt this should help you shallow out the plane.

I went to the range a few times this weekend to try a few of the things listed above.  Turning my shoulders more on the backswing and then sliding my hips forward on the downswing seemed to help.  I just have to go practice more to see if I can make it repeatable every time.  Something was working as I didn't slice any like I usually do.  The ball was going straight, just not always where I wanted it to go.

Thanks for the feedback everyone.