Generally a brake does not to be indexed to the barrel. Peel off washers can be used to adjust the alignment. Some brakes do require indexing to the barrel, A brake that has a primary design to eliminate muzzle jump will push the muzzle off in the wrong direction if not properly done. I feel that all brakes should be completed and installed by the manufacturer of the devise. A nice smooth seamless transition from barrel to brake that looks like it was machined to the barrel because it was. A real good brake will be designed with the actual barrel length, contour and cartridge in mind. Although a prepackaged brake will reduce recoil very well as far as accuracy and looks is concerned they will not compare with a custom one!