Did not look at NECG site, but usually accessories to be mounted on the barrel are cataloged by Diameter. For instance: Super Sourdough Sight # 42 for installation on barrels .648" to .679 in diameter. Can't recall seeing a sight or band asking for Radius. In any event radius will obviously be half the diameter. One screw is sufficient, but for peace of mind I usually use LocTite 680 or Stud and Bearing Mount under the entire surface. The heat in soldering makes me nervous being unevenly applied to such a small area. Don't know your barrel profile but I like post 64 Winchester factory sights with 2 screws each, you can find them used on Ebay most of the time. I may have a pair here someplace. Paul
