Is there any difference in action between the large and small loose ring?

Neue Schule has scientifically researched the difference between ring sizes and found there was no mechanical advantage to choosing a larger or smaller loose ring, and ring size will not alter the action of the bit. A larger ring is often employed as a snaffle and the smaller ring is often used as a Bridoon. However, owners of ponies or horses with a smaller head may wish to use the smaller ring for aesthetic purposes as this tends to look more in proportion. The larger ring is also less likely to pull through the horse’s mouth than a smaller ring but may interfere with the noseband or rub the underside of the cheek bone.