When you pull the reins, there is less of a pinching action (nutcracker effect) with a double-jointed because of the positive width of the middle piece. Just take either bit, put your finger in the middle, and squeeze the outer parts together...
When you pull the reins, there is less of a pinching action (nutcracker effect) with a double-jointed because of the positive width of the middle piece. Just take either bit, put your finger in the middle, and squeeze the outer parts together...Question: why would a horse choose a double jointed over a single jointed, barring mouth conformation?