Thanks Roy. That seems to be what's happening here, at least in terms of distance from the muzzle. I don't think I saw a single patch that was still full width measured from base of bullet to nose. The bits I was seeing appear to be the portion of the patch inside the case and wrapping under the bullet.

Do you use wads directly under the bullet when firing NfB loads with filler (foam, Dacron or kapok?)

Chris