Love mine. Have used it for years. Very handy for volume loading. Just pitch a bullet through the window and run the case up. No pinched fingers, no fumbling. If you are asking if it seats bullets any straighter than others, I don't know. Don't spin mine. When it will seat bullets in varmint calibers straight enough to get below an inch I begin to quit worrying. It will seat my .308's well enough to shoot 3/4" with a BLR and 06's well enough to get 1.25" in a Browning '95 with tang sight.