Hello Jmac:

Here is a tip that may help your tendency to flip, swat, break down, cast....

Assuming a sound neutral or slightly strong grip, your right hand should hold the handle primarily in the fingers and you should be able to see 2 knuckles of the right hand while the club is at address. Most people talk about the left hand position but the right is equally important. Do not rotate the right hand under the club by clawing at it. If you do this you would not see any knuckles and this is a very detrimental position. Even the strongest grippers on the tours show the right hand as I've described.
This facilitates the proper right hand action in the swing.

When you grip the club, focus on keeping pressure where the underside of the right thumb covers the left thumb. Some drills advise sticking a piece of paper like a gum wrapper in between this area and focusing on swinging without the paper flying out. You do not need to grip the club tighly do do this and, in fact, you always want to maintain a light grip pressure overall. Just make sure that you maintain pressure where the thumbs overlap during the entire swing.

What happens when you flip or swat (casting is the initial death move resulting in both of these) you are creating separation between the thumbs at the top of the backswing or very early into the downswing. The right hand actually breaks away from the left and you are overpowering the left hand with the right with the cast move. By keeping pressure at the area I suggest, you will keep the hands working as a unit. I feel as if I'm using the fleshy portion of my right hand at the base of the of the thumb to push the left hand into a flat position at impact. This maintains the cupped right hand position at impact. The left wrist is straight and the right is cupped at impact with all good ballstrikers.

I made a training device using two golf gloves to enhance this feeling of hand connection. Where the thumbs overlap, I glued velcro strips so when I took my grip, this area was glued together so to speak. This really helped me feel the correct action of my hands during the swing working together. It really helps maintain the cupped position of the right hand.

I hope it helps you.