My early years riding western taught me the neck rein, and understanding the use of the neck rein to control the shoulder is what it’s all about. The direct rein can guide the nose, but the neck rein makes the shoulder follow the nose and the haunches have no choice but to stay on the line. The neck rein also makes the horse go straight, keeping the wither in a straight line between the nose and the tail. It can shape the body to match the turn when using the inside rein indirectly, which is inside rein to outside haunch. So while the inside rein is shaping the body, the outside rein has even pressure, regulates the pace and balances the horse.
This shape and balance is invaluable on course when making your turns. The horse can see the jump through the turn and also has the balance to jump right off the turn because the haunches carry the horse. This is also extremely valuable when riding in hunter classes where rhythm, balance and accuracy are vital. As well, if you see you are going to be a little tight at the jump you can open the turn by moving the shoulder out to make room, or if you are a little long you can close the turn by moving the shoulder in to get a little closer.
I train my horses to fade in and out from the neck rein and once they are educated I will almost never need to use the leg to support the neck rein. Needless to say, carrying your hands properly is vital in getting the best results. I like the hands carried above and in front of the wither and about as far apart as the width of the bit. Focus on keeping your rein length even and your hands parallel. I use this a lot in hunter classes, where I don’t have to pull or push to be accurate, I just open or close the turn. I even use it on the long diagonal where I always turn early to avoid a swap off and then keep a little bow in the approach which I can increase or decrease to be accurate at the jump and you never have to change the rhythm of the stride. It’s usually very subtle.
The real winning ticket, though, is in the jump-offs, where moving the shoulder on tight turns creates accuracy without an argument from your horse. You have the shoulder out and the haunches in for total balance, allowing your horse to jump right off the turn. The other turn using the neck rein is the turn on the haunches (or in western we called it the roll-back).
I teach my horses at home how to roll-back, I use my voice command for a halt (“whoa”) and at the same time move both my hands slightly in the direction I want to turn, so it becomes a combination of halt and turn. The key to that turn is not losing momentum, so I use outside leg on the turn and maybe a cluck for acceleration.
When I look at a course and see either of those turns in the jump-off, I know if I leave the jumps up it is pretty much my class to win!