If it helps anyone, this brake can be safely turned down to .850", per APA. I turned one down to .843" I believe it was to match a rem varmint contour. It was a 6.5 creed, not a magnum, though I don't think a magnum would hurt it. All of APA's brakes are awesome, my 260 AI recoils maybe as much as a .223 varmint wt. gun. Spot my own hits past 1400. Misses too!