The problem with getting a custom turret is not with the manufacturer it is usually the person who orders the turret. My suggestion is to forget all the computer programs. Get yourself out to the range with your rifle and the ammo you plan on using to make the custom turret.
Set up your target for your "ZERO" distance then get your rifle zeroed in on that target. Ounce that is done put your next target 100 yds farther away and aim at the center of that target and shoot a 3 to 5 shot group so you can measure how far your "GROUP" dropped from your "ZERO". Then put another target 100 yds. farther then your second target and aim at the center of that target and measure what the drop is from your "ZERO" then go another 100 yds. and do it again.
What you have done is made an ark that your bullet travels as it goes down range. This is the most important information you can give the turret manufacturer. Once he has this info he can plot his computer program by adjusting the velocity and other parts of the program to match the bullets ark and it's weight you have made your drop chart with.
This is exactly what I did and the custom turret I received a week later is dead nuts on.
Here you can read & see what I did the first time I tested it. I shoot a 6mm Norma BR. with Berger 105 gr. VLDs. My bullets drop like a rock, but the turret is dead on all the way out past 900 yds.
Testing new Vortex custom turret. - Georgia Outdoor News Forum
joseph