The barrel that is clamped to the bench never did bend. To measure it, I place a 6' straight edge along the top so it touches at the breech and muzzle, and select a number drill that will just pass in the biggest gap which I indicate with a marking pen, before bending. I bend in that fixture, and check for progress with that same drill bit. If there is no bend, I add more pressure with the clamp, and check again. With a Rice, Getz, or Colerain barrel, you can add some bend without trouble, but this is an unknown maker's barrel, possibly from Larry Zorne. You can see that that solid slab table is also bent toward the barrel, and yet, it never took a bend.
If you use the whack it on a tree method, seize the barrel by the breech end, rather than the muzzle, and strike the barrel somewhere in the round section up from the wedding band. And be careful not to add windage you don't want, by striking the barrel on the top rather than obliquely or on the side.
