How does NB address this roll in the toe of the bone? I thought the breakover was set about a 1/4" in front of p3.
It is. Same place as the roll in the outer hoof capsule across the sole would be. Blunter than the toe is shapedat its outer edge.
Does the natural barefoot horse address this roll?
Yes ,as lng as the foot has a chance to wear at all naturally,the roll across the toe is formed at *about* 1/4" forward of the tip of P3 through the natural wear mechanism including the anatomical fact that the sole callus is morew dense and wear resistant than the outer wall , and therefore stops the toe wear at the the callus.
The reason it comes out about 1/4" forward of P3 is incredibly simple.
It is due to the direction of the growth of the horn tubiles takes from the solar margin ofP3 t the ground. The horn grows at about same angle of the bone , and where the ends of the tubules reach the ground, they are about 1/4" forward of the bone edge, give or take a little depending on the angle of P3 and the thickness of the live horn of the sole.
Bigger feet a little more, small or club feet a little less.
And TOM, if you or anyone else doesn't like the term "sole callus" please do not start another off track dssertation on terminology, just call it whatevertheheckyouwant, like "non exfloliating sole ridge", or "waxy sole hump" or "roundy sole bump thing " or the barefoot favorite, "moonsickle" , or whatever. That thing is the thing that stops the toe wear where it does.
And it is consistantly positioned with the position of the coffin bone . It HAS to be where it is, because it grows from the solar margin of the bone.
AND the two corners of that whateveryouwanttocallit ridge are Ducketts "pillars" . The are usually a little bit wider than the rest of that ridge and consequently even stronger. Naturally worn breakover point consistanty occurs in a fairly straight line across the toe at the front of those pillars. 1/4" forward of the tip of P3, give or take a fraction.