So how critical is bullet run out and when does it start to affect goup size. .005 or more? Would it be noticable when shooting at 100 yards............I would guess that all improvment add up to better accuracy but some within themselfs can make a noticable difference. Has anyone used the Hornady Concentricity Gauge..........SO, it will eliminate bullet runout? Can it be used to measure case neck runout also?