Need advice, bad habit not stopping.
First a little background. For the past six months I have been riding a friends horse fairly regularly, about once a week. The horse is a 12 year old Arabian gelding. I have been riding western since I was young, 6 or 7.
The most glaring problem that is immediately noticeable is when the horse picks up speed, a gallop or run, it is almost impossible to stop. It's a nightmare like trying to stop a train with two strips of leather. I am used to neck reining and the horse responds to it very well at a walk or trot. The thing I am noticing is when the horse is running and I try to stop it does one of two things. First it turns it's head to the left or right, though it's 80% of the time to the left. When this happens I have to choice but to let slack in the reins. Trying to pull the head back straight, so it's facing forward, does nothing. I originally thought I didn't have the reins even so when I try to stop the horse, the left side was shorter so the horse naturally turned it's head. Lately I have been taking great care to not do this but I am starting to doubt if this is the only problem with my riding. For one if I let some slack on the left side the horse keeps it's head turned until the right side has slack too. (I've tried pulling only the right rein but this does nothing, the horse simply fights it.) I really think this is a problem with my riding because I am noticing that to stop the horse at a run I have to grab each rein and stop as if I were direct reining (pulling the reins down towards my knees.) Also I don't expect the horse to from a full run to a sudden stop but it doesn't even slow down.
This leads me to my second problem with stopping, even when I direct rein to stop it is still a lot of work. This is especially true when there are other horses ahead. As it goes right now I don't run the horse and at a gallop I am always having to keep it in check even if I have to stop the horse and walk it.
That is another problem. If other horses are running or galloping, especially if they pass, the horse will burst into a run to keep up or to close the distance if we are behind. I CANNOT STAND THIS, I have to struggle to keep the horse from blindly running after the other horses leading to the whole stopping problem.
I could really use some help with this. I am not used to having to overpower the horse just to stop. I'm used to a slight pull on the reins and the horse slows down. I cannot figure out what I am doing wrong or if it's the horse or both. Like I said before this isn't my horse though I have been using it almost exclusively for the past six months. Before that a lot of other people have ridden the horse and a lot of them shouldn't even be around horses to begin with. I have made progress in other areas of bad habits and the horse is not a bad horse. The owner doesn't mind if work with the horse by myself and train good habits into but I am simply at a loss on what to do with the stopping problem.