Advertised BC accuracy?

[Ruko]

Just wondering how accurate the advertised BC is for bullets. I am shooting a 7mm STW with Nosler Accubond 140gr. On the Nosler site it says they have a 485 BC but when I put my velocity info into the Vortex calculator it comes out as 525 BC. I was entering my data in order to get a turret made so I would like to be as accurate as possible but these seem to be quite different so it raised some alarms.

[tchardy1972]

The key is in the scope adjustment. A lot of scopes don't dial the actual .25 minutes they should. Some a little more, some a little less. The way to test is easy. Put a large sheet of paper up at 100 yards with a dot near the bottom. Shoot a group, the dial 20 moa in and shoot another group while aiming at the same dot. Now measure the distance between the centers of the groups. ( and be honest) if the is any discrepancy you should see it. I have one scope that dials .23 moa per click. With the right ballistic program you can figure it out by entering this info in. If you try to fix the numbers by fudging the b.c. numbers you will see it will give you the wrong trajectory curv if you shoot at more than one distance. You have to change the right numbers. P.m. me for further info.

This does not mean your scope is bad. The important thing is it does the same thing every time you turn the knobs.