I have seen Ashby's photos, and others, of single bevels "busting" every type of bone in various ways. Whether a shoulder blade is split horizontally, as in some published photos, or is merely cracked in any direction, the result is the same -- the bone opens up, easing the arrow's passage, netting better penetration. The point isn't to destroy bones, but to get penetration through them, which torquing single bevels do better than punch-through double bevels, not matter how they hit. Hundreds of repetitions of testing by Ashby prove this nicely. Dave