1-12 should work fine with properly sized, + 2 thousandths cast either well lubed or painted at 1400-2000 fps in the Magnificent 458 WM. I also shoot quite a few 30-06 cast at 1-10 at same velocities and that works fine too. What Ron says is in the correct direction though, he is not intending to use his 1-10 458 for cast when he has a plethora of 1-14's that will be better for that purpose. Gentler RPM is better on cast most folks agree.
