Diamond listens to me well at a walk, trot, canter, and slow/hand gallop, but when I increase his speed faster than that he pulls with the bit, and I have a huge problem slowing him down without doing strange, bumpy half-stops/leg plants as we both fight for control--Diamond is an extremely level headed horse, and actually most of the time is low-key and slow...but he really loves running. I would love to be able to move smoothly from a canter, to a hand gallop, to a full gallop, then back to a hand gallop, without resistance from him.
Again, he moves excellently from all other gaits, including hand galloping. It's just the full-blown gallop we have trouble with.
Anyone have any suggestions/tips?