I have one on my .338 win mag. I didn't like the idea of guessing how high to hold over thier backs. I followed leupolds instructions. for my caliber. I zeroed it at 200, put the 300 pin on at the 300 yard target. I was 1.5" low. Close enough for me. I didn't kill a elk with it yet, but it should definitly help on those 5 to 6 hundred yard shots.