Up until this year, I have dabbled with custom cut turrets for the scopes on my rifles. After handloading and finding the setup that gives good accuracy and SD's, I would order a custom turret using LabRadar verified velocities and the factory supplied BC's. After recently taking a long range shooting course (Barbour Creek) and learning the correct fundamentals, I decided to test my custom turrets. Out to 500 yards, mine were close. Beyond that, they were significantly off. I suspicion that the factory supplied BC's were not entirely accurate. Using a Sig Kilo8K with Applied Ballistics, I shot to 800 yards and then corrected for drops. I am now completely comfortable shooting out to that range and will continue practicing out to 1,000 yards. Point is, prior to taking the course, I falsely believed that these custom turrets were accurate to whatever range I wanted to shoot. Now, I know that wasn't the case.