You can regain control using the simple exercise I'll give you here. With repetition, it'll put you back in the driver's seat, and will help you gauge your horse's speed, so you can position him for a clean, razor-sharp turn.
- Take your horse to the arena location where you'd normally ask him to initiate a barrel run. Place one hand on the saddle horn and the other on the reins-just as you would on a run. Maintaining light rein pressure while sitting squarely, not forward in your saddle, ask him to lope halfway to the first barrel. This will enable you to balance yourself, and will help your horse set himself for the turn by tucking his hind legs under his body. (If he becomes chargy or anxious, stop him, then trot him to the midpoint.)
- At the halfway point, bring your horse down to an extended trot. Begin lifting his shoulder and positioning his front end for the turn by sliding your hand down the inside rein and slightly picking up on it, so your thumb is facing upward. Use neck-rein cues to guide him to a spot 6 to 7 feet to the side of the barrel, an area known as "the pocket."
- When your horse's nose is even with the barrel, ask him to stop. Immediately back up 1 or 2 steps, then settle for about 10 seconds. You want your horse to learn to rate himself going into the pocket, and by asking him to stop and settle there you're telling him to do so. The stop also rocks his weight onto his hindquarters; the back-up causes him to drive his inside hind pivot foot under his body, properly positioning him for a strong push off when exiting the turn; the settle will take the "rush" out of his maneuver. If your horse won't stand completely still, do the best you can, gradually asking him to settle longer with each repetition.
- Ask your horse to walk around the barrel. As you make the turn, look at the barrel and evaluate your and your horse's position. If your horse drops his shoulder (his front end will become heavy and it'll feel like he's leaning against your inside rein and leg), pick up on your inside rein to lift his shoulder. Apply inside or outside rein pressure as needed to adjust his position. Circle the barrel at least twice to keep him from prematurely exiting the turn, which often leads to a too-wide exit.
- With practice at slower gaits, your and your horse's form will become automatic when you increase your speed. Here's the final result : My horse's shoulder is upright and balanced, his front legs are reaching and pulling the ground toward him, and his inside pivot foot is planted under his body. We can take this turn to the bank.